Mattis, in Seoul, says US can't accept nuclear North Korea

SEOUL (Reuters) - U.S. Defense Secretary Jim Mattis said on Saturday that he could not imagine United States ever accepting a nuclear North Korea, warning that its rapidly advancing nuclear and missile programs would undermine, not strengthen, its security.

Mattis has been at pains during his week-long trip to Asia to stress that diplomacy is America's preferred course, a message he returned to after top-level military talks in Seoul on Saturday and at the tense border area with North Korea on Friday.

Still, he warned Pyongyang that its military was no match for the U.S.-South Korean alliance, and that diplomacy was most effective "when backed by credible military force."

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Kim Jong Un observes North Korea's mid-September missile launch
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Kim Jong Un observes North Korea's mid-September missile launch
North Korean leader Kim Jong Un watches the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT. TPX IMAGES OF THE DAY
North Korean leader Kim Jong Un guides the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
North Korean leader Kim Jong Un guides the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
North Korean leader Kim Jong Un guides the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
North Korean leader Kim Jong Un (not pictured) guides the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT. TPX IMAGES OF THE DAY
North Korean leader Kim Jong Un guides the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
North Korean leader Kim Jong Un guides the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
North Korean leader Kim Jong Un guides the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
Officials react after North Korean leader Kim Jong Un (not pictured) guided the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
North Korean leader Kim Jong Un guides the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
North Korean leader Kim Jong Un (not pictured) guides the launch of a Hwasong-12 missile in this undated combination photo released by North Korea's Korean Central News Agency (KCNA) on September 16, 2017. KCNA via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
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"Make no mistake - any attack on the United States, or our allies, will be defeated. And any use of nuclear weapons by the North will be met with a massive military response that is both effective and overwhelming," Mattis said.

Mattis's South Korean counterpart, Defense Minister Song Young-moo, dismissed the idea of deploying tactical nuclear weapons to the peninsula as a response to the North's advances.

But the U.S.-Korean alliance had the ability to respond, even in the event of a nuclear attack from the North, Song added.

Tension between North Korea and the United States has been building after a series of nuclear and missile tests by Pyongyang and bellicose verbal exchanges between North Korean leader Kim Jong Un and President Donald Trump.

The CIA has said North Korea could be only months away from developing the ability to hit the United States with nuclear weapons, a scenario Trump has vowed to prevent.

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North Korea releases photo that appears to show new missile plan
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North Korea releases photo that appears to show new missile plan
North Korean leader Kim Jong-Un gives field guidance during a visit to the Chemical Material Institute of the Academy of Defense Science in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on August 23, 2017. KCNA/via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.
North Korean leader Kim Jong-Un gives field guidance during a visit to the Chemical Material Institute of the Academy of Defense Science in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on August 23, 2017. KCNA/via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.
North Korean leader Kim Jong-Un looks on during a visit to the Chemical Material Institute of the Academy of Defense Science in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on August 23, 2017. KCNA/via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.
North Korean leader Kim Jong-Un looks on during a visit to the Chemical Material Institute of the Academy of Defense Science in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on August 23, 2017. KCNA/via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.
North Korean leader Kim Jong-Un gives field guidance during a visit to the Chemical Material Institute of the Academy of Defense Science in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on August 23, 2017. KCNA/via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.
North Korean leader Kim Jong-Un looks on during a visit to the Chemical Material Institute of the Academy of Defense Science in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on August 23, 2017. KCNA/via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.
North Korean leader Kim Jong-Un looks on during a visit to the Chemical Material Institute of the Academy of Defense Science in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on August 23, 2017. KCNA/via REUTERS ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.
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Mattis, too, said Kim's behavior had left no room to imagine accepting Pyongyang's nuclear status.

"I cannot imagine a condition under which the United States can accept North Korea as a nuclear power," Mattis told a news conference.

Trump - who has threatened to destroy the North if necessary - leaves on his first trip as president to Asia next week, including a stop in South Korea to meet President Moon Jae-in.

Moon, after talks with Mattis on Friday, said the "aggressive deployment" of U.S. strategic assets in the region, which have included overflights by U.S. bombers, had been effective in deterring the North Korean threat.

DENUCLEARIZE?

U.S. intelligence experts say Pyongyang believes it needs the nuclear weapons to ensure its survival and have been skeptical about diplomatic efforts, focusing on sanctions, to get Pyongyang to denuclearize.

RELATED: North Korea's missiles

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North Korea's Missiles
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North Korea's Missiles
The scene of the intermediate-range ballistic missile Pukguksong-2's launch test in this undated photo released by North Korea's Korean Central News Agency (KCNA) May 22, 2017. KCNA/via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
The long-range strategic ballistic rocket Hwasong-12 (Mars-12) is launched during a test in this undated photo released by North Korea's Korean Central News Agency (KCNA) on May 15, 2017. KCNA via REUTERS REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.
Missiles are driven past the stand with North Korean leader Kim Jong Un and other high ranking officials during a military parade marking the 105th birth anniversary of North Korea's founding father, Kim Il Sung, in Pyongyang, April 15, 2017. REUTERS/Sue-Lin Wong
North Korean leader Kim Jong Un inspects the long-range strategic ballistic rocket Hwasong-12 (Mars-12) in this undated photo released by North Korea's Korean Central News Agency (KCNA) on May 15, 2017. KCNA via REUTERS REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT. TPX IMAGES OF THE DAY
People cheer as a missile is driven past the stand with North Korean leader Kim Jong Un and other high ranking officials during a military parade marking the 105th birth anniversary of country's founding father Kim Il Sung, in Pyongyang April 15, 2017. REUTERS/Damir Sagolj
Military vehicles carry missiles with characters reading 'Pukkuksong' during a military parade marking the 105th birth anniversary of country's founding father, Kim Il Sung in Pyongyang, April 15, 2017. REUTERS/Damir Sagolj TPX IMAGES OF THE DAY
North Korean leader Kim Jong Un supervised a ballistic rocket launching drill of Hwasong artillery units of the Strategic Force of the KPA on the spot in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang March 7, 2017. KCNA/via REUTERSATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. TPX IMAGES OF THE DAY
A fire drill of ballistic rockets by Hwasong artillery units of the KPA Strategic Force is pictured in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang September 6, 2016. KCNA/via Reuters ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NO THIRD PARTY SALES. SOUTH KOREA OUT. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.
FILE PHOTO - An underwater test-firing of a strategic submarine ballistic missile is seen in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on April 24, 2016. KCNA/File Photo via REUTERS. ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. SOUTH KOREA OUT.
A view of a firing contest among multiple launch rocket system (MLRS) batteries selected from large combined units of the KPA, in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on December 21, 2016. KCNA/via Reuters ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NO THIRD PARTY SALES. SOUTH KOREA OUT. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.
Ballistic rocket is seen launching during a drill by the Hwasong artillery units of the KPA Strategic Force in this undated picture provided by KCNA in Pyongyang on July 21, 2016. KCNA/via ReutersATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. SOUTH KOREA OUT. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS.Ã TPX IMAGES OF THE DAY
A test launch of ground-to-ground medium long-range ballistic rocket Hwasong-10 in this undated photo released by North Korea's Korean Central News Agency (KCNA) on June 23, 2016. REUTERS/KCNA ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. TPX IMAGES OF THE DAY
A new multiple launch rocket system is test fired in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang March 4, 2016. REUTERS/KCNA ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. NO THIRD PARTY SALES. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA
A rocket is launched during a demonstration of a new large-caliber multiple rocket launching system attended by North Korean leader Kim Jong Un (not pictured) at an unknown location, in this undated file photo released by North Korea's Korean Central News Agency (KCNA) on March 22, 2016. REUTERS/KCNA/Files ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. TPX IMAGES OF THE DAY
A rocket is fired during a drill by anti-aircraft units of the Korean People's Army (KPA) in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang November 3, 2015. REUTERS/KCNA ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. NO THIRD PARTY SALES. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA.
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Mattis suggested, however, that Pyongyang needed to understand that its weapons programs would not strengthen its defenses. The North says it wants a nuclear-tipped missile capable of reaching the United States.

"If it remains on its current path of ballistic missiles and atomic bombs, it will be counter-productive," Mattis said, adding North Korea would be "reducing its security."

Still, any attempt to force the North to denuclearize could have devastating consequences, thanks in part to the large amount of artillery trained on Seoul.

During Mattis' trip to the inter-Korean Demilitarized Zone (DMZ) on Friday, he was briefed on the posture of North Korean artillery.

Defense Minister Song suggested that U.S. and South Korean missile defenses simply could not stop all of the weapons trained on the South.

"Defending against this many LRAs (long-range artillery) is infeasible in my opinion," Song told Mattis at the DMZ, citing a need for strategies to "offensively neutralize" the artillery in the event of a conflict.

Mattis replied: "Understood."

Still, Mattis reaffirmed to reporters in South Korea that military options do exist to deal with the North Korean threat that spare the South's capital, Seoul. Mattis, who has made such assurances in the past, did not disclose what those options were.

(Additional reporting by James Pearson in Seoul; Reporting by Phil Stewart; Editing by Nick Macfie)

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