US-led meeting urges North Korea pressure despite North-South detente

"It is not the time to ease pressure, or to reward North Korea," he said. "The fact that North Korea is engaging in dialogue could be interpreted as proof that the sanctions are working."

Tillerson said North Korea must not be allowed "to drive a wedge" through allied resolve or solidarity and reiterated Washington's rejection of a Chinese-Russian proposal for the United States and South Korea to freeze military exercises in return for a freeze in North Korea's weapons programs.

Tillerson said the group in Vancouver, which supported South Korea during the 1950-53 Korean War, would aim to improve the effectiveness of the U.S.-led "maximum pressure" campaign on Pyongyang.

He urged China and Russia to fully implement U.N. sanctions.

China and Russia, which backed the North in the war, have sharply criticized the meeting, which was announced after North Korea tested its biggest ever intercontinental ballistic missile last November, as an example of "Cold War" thinking. While both have signed up to U.N. sanctions, they have been accused of not doing enough to ensure proper implementation, something they deny.

"We cannot abide lapses or sanctions evasion," Tillerson said. "We will continue to call attention to, and designate, entities and individuals complicit in such actions."

Tillerson said all countries needed to work together to improve interdiction of ships attempting to skirt the sanctions and said there must be "new consequences" for North Korea "whenever new aggression occurs."

A senior State Department official told reporters every country had a role to play, whether it was in sharing intelligence or refusing to allow ships that have engaged in illicit activity into their ports.

The White House has welcomed news that China's imports from North Korea plunged in December to their lowest in dollar terms since at least the start of 2014, but U.S. President Donald Trump accused Beijing last month of allowing oil into North Korea.

Western European security sources told Reuters last month Russian tankers had supplied fuel to North Korea on at least three occasions in recent months by transferring cargoes at sea.

Earlier on Tuesday, Chinese state media said Chinese President Xi Jinping told Trump in a phone call that unity on the North Korean issue was extremely important and the hard-earned easing of tensions must continue.

The White House said Trump and Xi both expressed hope that the resumption of North-South dialogue might prompt a change in Pyongyang's "destructive behaviour."

North and South Korea held formal talks for the first time in two years this month and Pyongyang said it would send athletes to the Olympics.

South Korean Foreign Minister Kang Kyung-wha said in Vancouver she hoped the dialogue would continue well beyond the Olympics, but stressed that existing sanctions must be applied more rigorously.

"These two tools - tough sanctions and pressure on the one hand, and the offer of a different, brighter future on the other - (have) worked hand in hand," she said.

U.S. officials say hawks in the Trump administration remain pessimistic that the North-South contacts will lead anywhere.

Even so, they say debate within the U.S. administration over whether to give more active consideration to military options, such as a pre-emptive strike on a North Korean nuclear or missile site, has lost momentum ahead of the Olympics.

U.S. national security adviser H.R. McMaster, who has appeared the more hawkish of Trump's top aides, met in San Francisco at the weekend with Japanese Prime Minister Shinzo Abe's top national security adviser and a senior South Korean official, a U.S. official said.

The three discussed the North-South talks and a shared commitment to keep up the U.S.-led pressure campaign, the official said, speaking on condition of anonymity.

Brian Hook, the U.S. State Department's head of policy planning, told MSNBC the North-South talks were a positive step, but North Korea had been taking advantage of goodwill gestures for decades and needed to "earn their way back to the negotiating table."

The senior State Department official said U.S. Defense Secretary Jim Mattis briefed the Vancouver participants over dinner on Monday and stressed the U.S. preference for a diplomatic solution, while keeping a military option on the table.

"It was a chance to raise people‘s confidence that we have thought through this, that we definitely prefer a diplomatic solution," the official said.

Diplomats say the absence of China, North Korea's main ally and trading partner, will limit what can be achieved from Vancouver.

The U.S. official said Susan Thornton, the State Department's senior diplomat for East Asia, would travel to Beijing from Vancouver to brief China on the outcome. He said he expected Tillerson to provide readouts to his Russian and Chinese counterparts.

China's main English-language newspaper, the China Daily, said the meeting was "poorly conceived" and would prove counter-productive.