The UN Security Council is preparing a response to North Korea after it test-launched two mid-range missiles, China's UN ambassador Liu Jieyi says.
The two launches on Thursday came after a similar test on 15 April.
Observers say all the tests appear to have failed, but a UN spokesman said such actions, which violate sanctions, were "deeply troubling".
It comes amid a recent ramp-up in weapons activity as the North prepares for a rare party congress.
There are also indications it is planning to carry out its fifth nuclear test, despite condemnation of its last test in January.
In a rare comment on the situation, Chinese President Xi Jinping said China - North Korea's closest ally - was committed to ensuring stability.
He told a meeting of regional foreign ministers in Beijing on Thursday: "As a close neighbour to the (Korean) peninsula, China will never allow war to erupt on the peninsula. Once such a situation occurs, it will do nobody any good."