The United States is planning to send warplanes and warships to the South China Sea in order to put pressure on China over its artificial islands in the region, American officials say. The Wall Street Journal reported on Tuesday that the Pentagon is considering using “aircraft and Navy ships to directly contest Chinese territorial claims to a chain of rapidly expanding artificial islands.” It also said US Defense Secretary Ashton Carter called for options that include flying surveillance aircraft over the islands and sending warships to within 12 nautical miles of the Spratly Islands. Beijing is building artificial islands in the South China Sea, saying the construction is in its own sovereign territory. However, Washington says the islands are made in international waters and it does not recognize the man-made islands as sovereign Chinese territory. The Journal reported American aircraft have so far flown close to the Chinese islands and the USS Fort Worth has been operating in the area in recent days. “We’re just not going within the 12 miles—yet,” an unnamed senior US official said. The USS Fort Worth Tensions between China and the US escalated in November 2013 after Beijing declared an air identification zone over the East China Sea. The US military flew a pair of B-52 bombers over the area in defiance to China’s move. The White House has not received the new plans by the Pentagon for sending the military to the region. American officials believe that the case is complicated because the US government considers at least some of the areas where the Chinese have been doing construction as legitimate islands. If approved by the White House, Navy ships and aircraft would be sent to within 12 nautical miles of the built-up sites that the US does not legally consider to be islands, according to officials.