US Secretary of State John Kerry has met Chinese President Xi Jinping, amid increasingly tense territorial rows between Beijing and Washington's security allies Tokyo and Manila.
Kerry started his Valentine's Day visit with a meeting with Xi at the Great Hall of the People, and was due to meet other officials including Chinese Foreign Minister Wang Yi later.
Kerry's trip comes at a pivotal moment for the region, with flaring disputes between Beijing and Tokyo over their World War II history and disputed islands in the East China Sea sending relations between the Asian powers plummeting to their lowest point in recent years.
Fears of an aerial or maritime clash over the islands have spiked following Beijing's recent declaration of an air defence identification zone in the skies above the East China Sea. Patrol boats from both countries regularly shadow each other in the waters near the islands.
At the same time Beijing has been acting increasingly assertively in the South China Sea, which it claims almost in its entirety.
In remarks on Thursday night before leaving Seoul, the first leg of his Asia trip, Kerry reaffirmed that the East China Sea islands, called Diaoyu by Beijing and Senkaku by Tokyo, fall under the security treaty that obliges the US to intervene on Japan's behalf if it is attacked by a third country.
"That is the position of the United States with respect to those islands," he said, referring to them by their Japanese name.
