BEIJING — China is entitled to strengthen its defenses on islands in the disputed South China Sea but those measures aren’t directed at any specific countries, a defense ministry spokesman said Tuesday, amid the latest surge in tensions in the crucial waterway.

China’s military deployments are “the natural right of a sovereign nation that helps safeguard national sovereignty and security,” Ren Guoqiang said in a statement posted on the ministry’s website.

They also help protect navigation safety, “serve to ensure regional peace and stability and are not directed at any country,” Ren said.

Ren gave no details, although his statement was a reply to a question about whether China’s deployments were a response to missions by the U.S. Navy to challenge Beijing’s claim to virtually the entire South China Sea.

That followed the U.S. Navy’s dispatching of three aircraft carriers to the South China Sea and a report in the Wall Street Journal newspaper on Monday that China has installed military jamming devices on two islands in the area.

China’s military buildup has focused on several islands in the Paracel group and seven that it built atop reefs in the highly contested Spratly group, topping them with airstrips, barracks and other defense infrastructure.

China has also reportedly been holding large-scale naval exercises in the area featuring its sole operating aircraft carrier, while its air force says it recently sent some of its most advanced fighters and bombers for “joint combat patrols” over the sea.

Those included H-6K long-range strategic bombers that carry DH-20 long-range land-attack cruise missiles, giving them the ability to hit targets as far away as Australia, along with Russian-made Su-35 fighters.

China’s claims in the South China Sea overlap in whole or in part those of Taiwan, Brunei, Malaysia, Vietnam and U.S. treaty partner the Philippines.

Washington doesn’t take a formal position on sovereignty claims in the area but regards the South China Sea largely as international waters in which its navy has the right to operate within legal confines.