US Secretary of State John Kerry is in China to urge Beijing to halt what is seen as its increasingly assertive actions in the South China Sea.
US officials say Mr Kerry will voice concerns over China’s land reclamation projects in the disputed waters.
China has warned it will defend its “legitimate rights and interests”.
China claims almost the whole of the South China Sea, resulting in overlapping claims with Brunei, Taiwan, the Philippines, Vietnam and Malaysia.
Mr Kerry’s visit comes as the Indian Prime Minister, Narendra Modi, is also in the country.
On Friday, Mr Modi and China’s Premier Li Keqiang said they agreed to seek a “fair resolution” to border disputes arising from a boundary disagreement.
This came after the two leaders held talks in Beijing’s Great Hall of the People.
Mr Kerry is due to hold a series of meetings with Chinese President Xi Jinping and other top government officials in the Chinese capital.
State Department officials say his visit has been scheduled for some time, but the agenda will now be dominated by China’s activities in the disputed waters.
Washington says China has reclaimed about 810 hectares of land (2,000 acres) of land in the Spratly Islands since 2014.
It says that while the aim of the expansion activity remains unclear, China is “improving its defence infrastructure in the South China Sea”.
Ahead of Mr Kerry’s visit, China said it would defend its national interests in the region.
“China’s determination to defend national sovereignty and its legitimate rights and interests is unswerving,” foreign ministry spokeswoman Hua Chunying.
“We will adopt stern measures to counter any acts that will pose provocations and threats against China.”
Beijing has also expressed concern over reports that the US may send its military ships and aircraft to assert freedom of navigation in the South China Sea – one of the world’s busiest shipping areas.