An expert on North Korea says the escalating tension in the region explains the sudden Chinese interest in cooperation with the United States.

LISTEN ABOVE: North Korea expert Rudiger Frank of the University of Vienna spoke to Nadine Higgins on Rachel Smalley Early Edition

North Korea is vowing to continue missile testing, while US the says the era of strategic patience with North Korea is over.

Rudiger Frank at the University of Vienna told Nadine Higgins China doesn't want a military conflict.

But he said Washington would be naive if they they think the Chinese are now going play to their tune.

"I think on the contrary, the Chinese are concerned about what Washington's going to do. They want to keep them close to have an eye on what Mr Trump is doing and this why they offered this kind of cooperation."

Visiting the demilitarised zone over the weekend, US Vice president Mike Pence made it clear the era of strategic patience with North Korea is over.

Mr Frank told Nadine Higgins China knows it's only a matter of time before the whole Korean Peninsula will become Chinese allies.

"They are really concerned that the Americans might do something rash. They want to prevent that by signalling some kind of cooperation, but in the long run what the Chinese are doing is just playing for time."

North Korea's deputy ambassador to the UN, Kim In Ryong, is accusing Donald Trump's administration of acting like thugs and is helping to push things to the brink of war.

"The United States is disturbing global peace and stability and insisting on gangster-like logic."

CNN's Jim Acosta said there's talk of the era of so-called strategic patience, coming to an end.

"You hear the President say this morning at the Easter Egg Roll that Kim Jong Un and the North Koreans 'gonna behave'. That's not exactly toning things down or ignoring the North Korean problem. They're essentially saying at this point 'don't dare us'."

The White House is expected to say more in its regular press briefing this morning.