150,000 troops are said to have been sent to the North Korean border. AP Images China and South Korea have signaled they would take a stand against North Korea if it conducted another nuclear or intercontinental ballistic missile test, according to reports.

China's state-owned newspaper, Global Times, has unconfirmed reports that China's army had sent 150,000 troops to the border with North Korea and that South Korea was conducting military drills in the border area.

The reports follow concerns that the North would use a national commemoration on the weekend to conduct its sixth nuclear test.

China's intervention would be praised by US President Donald Trump, who has been pushing for the Asian superpower to take action against the North.

The US has sent a Navy strike group toward the Korean peninsula.

While US Defence Secretary Jim Mattis hasn't said what the US aircraft carrier is up to near North Korea, Trump tweeted on Tuesday: "North Korea is looking for trouble. If China decides to help, that would be great. If not, we will solve the problem without them! U.S.A."

North Korea has since warned that a nuclear attack on the US would be imminent should the Trump administration show signs of aggression in the western Pacific.

According to Rodong Sinmun, North Korea's official newspaper, the army "is keenly watching every move by enemy elements with our nuclear sight focused on the US invasionary bases not only in South Korea and the Pacific operation theater but also in the US mainland."

US Vice President Mike Pence will meet Australian Prime Minister Malcolm Turnbull on April 22 for talks that are expected to be centered on regional security and North Korea.