North Korea kicked off the new year with three missile tests in the space of two weeks, sparking reactions from Washington not seen since Pyongyang stopped testing its longest-range missiles, which can strike the United States, in 2017.
At least two of the latest tests were of what North Korea called "hypersonic missiles" while details on the third, launched on Friday, were not immediately available.
Those hypersonic missiles, which have only regional reach, are not a threat to the continental United States. But the weapons - which can fly below defences and change course at high speed - represent a potential major upgrade in North Korea's striking power against its nearby adversaries, and experts say it is unclear how the U.S. and its Asian allies could counter that.