China will send nuclear weapons to patrol the South China Sea amid rising tensions with the U.S. over the disputed region, the Guardian reported Thursday. The area has become a point of contention between the U.S. and China, as Beijing claims it has sovereignty over the zone. The U.S. says the area is in international waters until competing land claims from neighboring countries are resolved.

Beijing is expected to send submarines equipped with nuclear missiles to patrol the region after working on the technology for ballistic missile submarines for nearly three decades. However, Chinese military authorities did not say when exactly these nuclear patrols would begin.

Because China’s SSBNs [nuclear missile submarines] are in the South China Sea, the U.S. navy will try to send spy ships in there and get close to the SSBNs. China’s navy hates that and will try to push them away,” Wu Riqiang, an associate professor at the School of International Studies at the Renmin University in Beijing, told the Guardian.

China has submitted a vast land claim over the region and sought to bolster that claim by building artificial islands in the South China Sea, including the Spratly Islands. While the islands are small and mostly unpopulated, they sit in the middle of popular trade routes and could also contain precious natural resources. The Philippines, Vietnam, Malaysia, Taiwan and Brunei, have also submitted competing claims over some part of the region.

The U.S. has accused China of militarizing the zone, and the U.S. military sent ships to sail through part of the South China Sea that Beijing claims as its own as a way to insist that the region is in international waters. The announcement of the planned use of nuclear-armed submarines came little over a week after two Chinese fighter jets nearly collided with a U.S. military reconnaissance aircraft in the region.