The U.S. Navy plans to challenge China's territorial claims in the South China Sea within the next two weeks by sailing warships near newly built artificial islands inside the 12-nautical-mile territorial limit that China has established, according to the Navy Times.

U.S. officials told the Times that once the Obama administration gives final approval, which could happen within days, the Navy will send ships through the contested space in the vicinity of the Spratly Islands, which would be the first time since 2012 that the U.S. Navy has directly challenged Chinese expansion in the area.

Since reports of Chinese land reclamation projects began surfacing in 2013, the U.S. and other regional actors like the Philippines have disputed its legitimacy and labelled it as an act of aggression. At least four other governments have also staked claims over part, or all, of the region.

Washington does not believe the man-made islands constitute sovereign territory and is attempting to build a legal case to support their position under international law, according to the Associated Press. The U.S. insists that the area, which includes vital sea lanes and airspace, must remain free from territorial control to allow for unrestricted navigation.

Chinese Foreign Ministry spokeswoman Hua Chunying said Thursday in a news briefing that China was paying close attention to the reports of U.S. naval action and expressed "serious concern about it."

"I believe the U.S. side is extremely clear about China's relevant principled stance," Hua said, noting that the two countries have maintained "extremely thorough communication" on the issue. "We hope the U.S. can look upon the current situation of the South China Sea from an objective and fair perspective and play a constructive role together with China in keeping the peace and stability in the South China Sea."

During Chinese President Xi Jinping's visit to the U.S. in late September, U.S. President Barack Obama expressed his "significant concerns" about the islands. Xi claimed that China plans to militarize the islands, which analysts in Washington say has already begun with the development of military facilities, including runways for aircraft. Now, the only question is how much military equipment it will station on the islands, according to Reuters.