The US and South Korea have held a ballistic missile drill after North Korea tested long-range missile experts believe may reach Alaska. Self-restraint was "all that separated armistice and war" and could be changed at any time, the two allies said.
It would be a "grave mistake" for the North to think otherwise, they said.China and Russia have urged both sides to stop flexing their military muscle and said they opposed any attempts at regime change in North Korea.
China and Russia have urged both sides to stop flexing their military muscle and said they opposed any attempts at regime change in North Korea.
Meanwhile, US President Donald Trump questioned Beijing's commitment to countering North Korea's nuclear threat, apparently citing China's first-quarter trade figures.
"Trade between China and North Korea grew almost 40 percent in the first quarter. So much for China working with us - but we had to give it a try!" he tweeted.
The missile launch, the latest in a series of tests, was in defiance of a ban by the United Nations Security Council (UNSC).
The US had asked for an urgent meeting of the UNSC to discuss the issue. A closed-door session of the 15-member body will take place later on Wednesday.
Pyongyang said last Tuesday had successfully tested an intercontinental ballistic missile (ICBM).
However, most experts believe that the North does not yet have long-range nuclear weapon capabilities.
The two Koreas are technically still at war as the 1950-1953 Korean War ended in an armistice.
Meanwhile, a joint statement by the commander of US Forces Korea, Gen Vincent Brooks, and South Korean Joint Chiefs Chairman, Gen Lee Sun-jin, said the allies were maintaining patience and self-restraint, but this could change.