BEIJING (Reuters) – China on Thursday responded to a Reuters report that the U.S. and India are discussing joint naval patrols in the disputed South China Sea, warning that interference from countries outside the region threatens peace and stability.

“No cooperation between any countries should be directed at a third party,” Chinese Foreign Ministry spokesman Hong Lei said in an emailed statement to Reuters, in response to a request for comment on the report published on Wednesday.

“Countries from outside the area must stop pushing forward the militarization of the South China Sea, cease endangering the sovereignty and national security of littoral countries in the name of ‘freedom of navigation’ and harming the peace and stability of the region.”

The United States wants its regional allies and other Asian nations to adopt a more united stance against China over the South China Sea, where tension has spiked since China’s construction of seven islands in the Spratly archipelago.

China lays claim to most of the South China Sea, while Brunei, Malaysia, the Philippines, Taiwan and Vietnam have rival claims.

A U.S. defense official told Reuters this week the United States and India had held talks about joint naval patrols that could include the South China Sea.

The Indian navy has never carried out joint patrols with another country and a navy spokesman told Reuters there was no change in the government’s policy of only joining an international military effort under the U.N. flag.

Neither the United States nor India have claims to the area, but the United States says it is concerned about shipping lanes running through the South China Sea, which carry an estimated $5 trillion of trade every year.

Hong urged caution.

“We hope that the relevant parties speak and act with caution, refrain from intervening in the South China Sea issue, and especially avoid being manipulated by certain countries and ultimately harming their own interests.”

China illustrates its claim to almost the entire South China Sea with a “nine-dashed line” on maps, that loops far to the south, with sections far closer to the coasts of countries like the Philippines and Vietnam than to its shores.

China’s more assertive claim has included dredging to build up islands and the construction of air fields and shipping facilities on some reefs. It recently launched flights to one artificial island.

The United States has responded by sending navy ships close to the islands China claims. China has condemned that as provocative.

India has a long-running land border dispute with China, and has stepped up its naval presence far beyond the Indian Ocean in recent years, deploying a ship to the South China Sea almost constantly, an Indian navy commander said.

(Reporting by Megha Rajagopalan and Pete Sweeney)