Tillerson says world united against North Korea

US Secretary of State Rex Tillerson said on Monday that a UN Security Council vote to impose sanctions on North Korea showed that world powers were united behind a push for a denuclearised Korean peninsula.

The United Nations Security Council unanimously imposed new sanctions on North Korea on Saturday that could slash its $3 billion annual export revenue by a third.

The US-drafted resolution bans North Korean exports of coal, iron, iron ore, lead, lead ore and seafood following Pyongyang's two intercontinental ballistic missile tests in July.

It also prohibits countries from increasing the current numbers of North Korean labourers working abroad, bans new joint ventures with North Korea and any new investment in current joint ventures.

Speaking to journalists at a security forum in Manila, Washington's top diplomat said that Kim Jong-un's regime must halt ballistic missile tests if it wanted to talk to the United States about resolving the standoff.

He also said the new UN resolution states that parties involved in tensions on the Korean peninsula can have dialogue when conditions are right.

Earlier in the day, South Korean President Moon Jae-in and his US counterpart, Donald Trump, agreed to cooperate and apply maximum pressure on North Korea in a telephone call, as Chinese media warned of the limits of new UN sanctions.

During the hour-long phone call, Moon and Trump said they would continue cooperating to rein in North Korea, particularly ahead of a regular joint military drill set for late in August, South Korean presidential office spokesman Park Su-hyun told a media briefing.

Moon was also cited as saying there was a need to show North Korea the door to dialogue is still open, should Pyongyang give up its nuclear programme.

In a separate statement, the White House said the two leaders "affirmed that North Korea poses a grave and growing direct threat to the United States, South Korea, and Japan, as well as to most countries around the world."

"The leaders committed to fully implement all relevant resolutions and to urge the international community to do so as well," the White House said.

North Korea has accused the United States and South Korea of escalating tensions by conducting military drills. North and South Korea are technically still at war because their 1950-53 conflict ended in a truce, not a peace treaty.