US senator compares Trump to a 5-year-old

A U.S. Senator has compared Donald Trump's maturity to that of a five-year-old child.

On Thursday, Senator Jeff Merkley appeared on MSNBC and was asked by host Chris Hayes about the president-elect's recent tweet which states that "The United States must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes."

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The Democrat from Oregon responded by saying, "This is an area where it's constrained by international agreements, as it should be, because of the risk of nuclear weapons."

Merkley later added, "There's really so much at risk here of irrational action. And right now, we have an incoming president who has kind of the maturity of a five-year old wrapped by a massive ego, and to have that just a second away from a nuclear trigger is very, very scary."

Despite attempts by Trump's team to clarify his statement, the president-elect reportedly told MSNBC's Mika Brzezinski on Friday, "Let it be an arms race. We will outmatch them at every pass and outlast them all."