HONG KONG — A top Chinese official said Thursday that American military drills and surveillance flights in the South China Sea were threatening regional stability, a harsh assessment that seemed likely to heighten tensions between the two countries before several crucial meetings.

The official, Col. Yang Yujun, a spokesman for the Ministry of National Defense, said it was the United States, not China, that was to blame for rising tensions in the resource-rich South China Sea, where China and several other countries are engaged in territorial disputes.

“The Chinese side expresses its deep concern about the United States pushing the militarization,” Colonel Yang said at a news conference in Beijing. “The behavior by the United States can only lead one to suspect whether the American side is driven by a desire to see the world in turmoil.”

The dispute over the South China Sea, one of the world’s busiest trade routes, has emerged as a serious point of contention between China and the United States.