US President Barack Obama and his Chinese counterpart Xi Jinping have agreed to fully implement sanctions against North Korea, in a meeting that was promptly followed by a provocative Pyongyang missile launch.

The White House said Friday that Obama and Xi agreed to "narrow differences" between the world's two major powers during a meeting the day before.

"Both leaders committed... to strengthen coordination in addressing the shared threat presented by North Korea's pursuit of nuclear weapons and ballistic missile systems," the White House said.

"Both leaders affirmed their commitment to achieving the denuclearization of the Korean Peninsula and the full implementation of UN Security Council Resolution 2270."

In January, North Korea detonated a nuclear device and a month later launched a long-range rocket, prompting the United States, China and other UN partners to implement sanctions.

Washington's efforts to build pressure on North Korea has long been a point of friction with Beijing, which provides the hermit state an economic lifeline.

The White House believes that China could do more to press North Korea into abandoning its nuclear and missile programs.

China fears that too much pressure would topple the regime, prompting instability and regional upheaval.

As if to underscore the difficult of the issue, North Korea on Thursday appeared to fire another short-range missile off its east coast.

South Korea's defense ministry said a surface-to-air missile was fired at around 12:45 pm (0345 GMT) from the eastern city of Sondok. The range and precise trajectory could not immediately be confirmed, a ministry official said.

- Forge consensus -

The launch came in the middle of the two-day nuclear security summit being hosted by Obama in Washington, at which North Korea has been the focus of the US president's talks with the leaders of China, South Korea and Japan.

The summit opened Thursday with Obama trying to forge consensus among East Asian leaders on how to respond to Pyongyang's recent nuclear and missile tests, which have seen an escalation of tensions in the region.

"We are united in our efforts to deter and defend against North Korean provocations," Obama said after meeting Japanese Prime Minister Shinzo Abe and South Korean President Park Geun-Hye.

The leaders also discussed the deployment of the sophisticated missile system THAAD -- the Theater High Altitude Area Defense System -- to South Korea.

But the move has raised concerns in Beijing, which is unhappy at the prospect of the US hardware on its doorstep, fearing it will further tip the balance of power in the Pacific towards Washington.

"It in no way threatens either Chinese or Russian or other security interests in the region and will do nothing to undermine strategic stability between the United States and China," insisted Dan Kritenbrink, Obama's top Asia adviser.

- Pragmatic gains -

During Obama and Xi's meeting Thursday, the White House said the two countries had agreed to sign the Paris Climate Accord and work toward a "global market-based measure for addressing greenhouse gas emissions from international aviation."

Obama and Xi have tried to use agreement on environmental issues as a ballast to stabilize relations beset by disputes over hacking of US government sites, the South China Sea and piracy.

"Both leaders reaffirmed the cyber commitments announced during President Xi's September 2015 State Visit and agreed to ensure their full implementation," said the White House.

"The President reiterated that we will continue to monitor whether Chinese actions demonstrate their adherence to the commitments."

There appeared to be less common ground over Beijing's alleged military buildup in the South China Sea.

US officials have expressed concern that China's actions are not consistent with Xi's pledge at the White House last year not to pursue militarization of the hotly contested and strategically vital waterway.

China claims virtually all the South China Sea despite conflicting claims by Brunei, Malaysia, Vietnam, Taiwan and the Philippines, and has built up artificial islands in the area in recent months, including some with airstrips.

"The President urged China to address differences with its neighbors on maritime issues peacefully and in accordance with international law and emphasized the United States global interest in upholding freedom of navigation and overflight," the White House said.

Washington has since October carried out two high-profile "freedom of navigation" operations in which it sailed warships within 12 nautical miles of islets claimed by China.