U.S. Secretary of State John Kerry is in China to press Beijing to halt increasingly assertive actions it is taking in the South China Sea.

Kerry arrived in Beijing on Saturday amid verbal sparring between U.S. and Chinese officials over land reclamation projects China is conducting in disputed waters.

China has reacted angrily to suggestions the U.S. may send military ships and planes to challenge Chinese claims to islands it is building. On Friday, Beijing reaffirmed that it will defend those claims and won't remain passive if they are threatened.

The claims have rattled the region where South China Sea islands and reefs are contested by China and five other Asian governments. The U.S. says it takes no position on the sovereignty claims but insists they must be negotiated.