The threat posed by North Korea dominated phone calls between US President Donald Trump and the leaders of China and Japan, along with trade issues, the White House said on Sunday.
Trump spoke with Chinese President Xi Jinping and Japanese Prime Minister Shinzo Abe ahead of expected meetings with the leaders of Asia's two biggest economies at a Group of 20 nations or G20 summit in Germany later this week.
"Both leaders reaffirmed their commitment to a denuclearized Korean Peninsula," the White House said of Trump's call with Xi from his resort property in Bridgewater, New Jersey, where he is spending a long weekend.
"President Trump reiterated his determination to seek more balanced trade relations with America's trading partners," it added.
Trump has become increasingly frustrated with China's inability to rein in North Korea, and the reference to trade was an indication the one-time New York businessman may be ready to return to his tougher-talking ways on business with Beijing after holding back in hopes it would put more pressure on Pyongyang.
Trump and Xi discussed the "peace and stability of the Korean peninsula", China's Foreign Ministry said, without elaborating.
Ministry spokesman Geng Shuang later told a daily briefing that the US was "very clear" about China's position on North Korea. Geng did not elaborate on what Xi told Trump about North Korea.
"Negative factors" have affected Sino-US relations, and China has already expressed its position to the US, Xi told Trump, according to a read-out of a telephone call between the leaders carried by the ministry.
Ahead of the phone call, China denounced a US warship sailing close to a disputed island in the South China Sea occupied by Beijing as a "serious political and military provocation", a move that could further strain relations between the two countries.
Beijing dispatched military vessels and fighter planes in response to warn the US vessel, foreign ministry spokesman Lu Kang said in a statement late on Sunday night, state news agency Xinhua reported.
The USS Stethem destroyer passed less than 12 nautical miles (22 kilometres) from tiny Triton Island in the Paracel Islands archipelago, which is also claimed by Taiwan and Vietnam, a US official said.
"The Chinese side strongly urges the US side to immediately stop such kind of provocative operations that violate China's sovereignty and threaten China's security," the Chinese spokesman said.
He also added that Beijing would continue to take all necessary means to defend national sovereignty and security.
The ministry said Trump told Xi the US government would continue to follow a "one China" policy, under which Washington acknowledges the Chinese position that there is only one China and Taiwan is part of it, and that this position had not changed.
Trump's separate conversations with the two Asian leaders followed White House talks with South Korea's new president, Moon Jae-in last week in which the US leader called on Asian powers to implement sanctions and demand North Korea "choose a better path and do it quickly."
Trump and Abe, in their call, reiterated their commitment to increase pressure on North Korea.
"They reaffirmed that the United States-Japan Alliance stands ready to defend and respond to any threat or action taken by North Korea," the White House said in a statement.
Japan's Chief Cabinet Secretary Yoshihide Suga told a news conference the two countries and South Korea will have a trilateral summit at the G20 meeting.
"It's important for these three nations to show their strong unity and cooperation both within and without," Suga said. "Things such as strengthening pressure on North Korea or urging China to fulfil even more of a role. Things like this have been agreed on before as well."