North Korea launched an intercontinental ballistic missile test on Saturday, sending shock waves through the volatile situation, but the test failed as the missile fell inside North Korean territory.
Trump's nearly admiring remarks came amid soaring tensions with North Korea over its missile and nuclear programmes, with an alarmed Washington looking to China for help in reining in Kim.
North Korea test-launched a missile on Saturday that appeared to have failed within minutes, its fourth successive failed launch since March.
North Korea has kept the West on edge for weeks over signs it may conduct a sixth nuclear test, punctuated by a series of missile tests that have aroused U.S. fears that the regime may be close to developing a ballistic missile capable of hitting the United States mainland with a nuclear warhead.
This marked North Korea's fourth unsuccessful missile test since March.
But, the President would not discuss the possibility of military action - saying "I don't know.we'll see" when asked if another missile launch by North Korea would mean retaliation.
The type of missile used in Friday's test has yet to be officially determined.
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North Korea test-fired a missile over the weekend in apparent defiance of a concerted United States push for tougher global sanctions to curb Pyongyang's nuclear weapons ambitions.
But, so far, perhaps nothing's happened. He added: "It is a chess game".
Refusing to elaborate on U.S. military options because "we shouldn't be announcing all our moves", Mr Trump added: "It is a chess game. We can't allow it to happen".
He reiterated that the United States must be supported by its global allies if it is going to make any meaningful strides, adding: 'It's important for all of us to confront this regime...
TRUMP: I don't know. So eventually, [Kim Jong Un] will have a better delivery system.
McMaster praised President Trump for his "masterful" handling of his relationship with Chinese leader Xi Jinping. He was asked specifically what he would tell U.S. President Donald Trump, who has sent a U.S. carrier to conduct drills near the Koreas, and other leaders to try to diffuse the tensions.
North Korea disrespected the wishes of China & its highly respected President when it launched, though unsuccessfully, a missile today. Bad!