Two Chinese fighters have carried out an "unsafe" intercept of a US military aircraft over the South China Sea, the Pentagon says.
The incident happened in international airspace on 17 May as the US maritime reconnaissance aircraft carried out a routine patrol in the area, it added.
Tensions in the region have increased recently, with China and the US trading accusations over military activity.
Several nations claim territory in the resource-rich South China Sea.
A military official quoted by the Associated Press news agency said the US pilot was forced to descend about 200ft (60m) to avoid a collision.
The defence department said it was addressing the issue through military and diplomatic channels.