China and the United States should take appropriate steps in dealing with "disputes" so as to avoid damage to their increasingly important relationship, President Xi Jinping said on Sunday, at a time of sharp differences between the two countries over escalating tensions in the South China Sea. Xi met US Secretary of State John Kerry in Beijing's Great Hall of the People, telling him the "China-US relationship remains stable on the whole", according to Xinhua. Xi's assessment of the relationship between the world's two largest economies came a day after Kerry conveyed Washington's concern over Beijing's land reclamation activities around reefs in the Spratly archipelago. Ahead of Kerry's visit over the weekend, reports came out last week that US Defence Secretary Ash Carter had requested options to "assert freedom of navigation" by sending aircraft and warships within 12 nautical miles of Chinese-made artificial islands in the Spratly chain, prompting Beijing to flag "serious concerns". Watch: US Secretary of State John Kerry meets Chinese President Xi Jinping The New York Times reported on Sunday that China had re-engineered many of its long-range ballistic missiles to carry multiple warheads, which could affect the US plan to deploy more robust missile defences in the region. Citing developments such as increasing military-to-military exchanges and cooperation on major global issues, Xi said "the new type of China-US relationship has witnessed early harvest". At the same time, Xi told Kerry that the two countries should "manage, control and handle disputes in an appropriate way so that the general direction of the bilateral relationship will not be affected". "The broad Pacific Ocean is vast enough to embrace both China and the United States," Xi said. On Saturday, Kerry held talks with Chinese officials including Premier Li Keqiang and Foreign Minister Wang Yi, to prepare for the two countries' annual strategic and economic talks next month and Xi's visit to Washington in September. Shen Dingli, deputy director of Fudan University's Institute of International Studies, rejected the idea that tensions had risen due to China's land reclamation. "China's practices are in line with international law … and the US is not in a position to point fingers at China," he said. Xu Guangyu, a senior consultant with the China Arms Control and Disarmament Association, said the US was applying pressure ahead of Xi's Washington trip. "The US is testing China's reactions. By taking a tough stance on China, the US side hopes China can make some compromises on the thorny issue of South China Sea disputes," said the retired PLA general. "But of course China will not back off, and Kerry will take this signal back to the US." Reuters, Kyodo, AFP Additional reporting by Li Jing