BEIJING, April 22 (Xinhua) -- China cautioned the United States to be discreet in its words and deeds regarding the South China Sea after U.S. Deputy Secretary of State Antony Blinken questioned China's intentions over its land reclamation project.

Blinken said on Thursday during his visit to Vietnam that China's land reclamation project and increasing militarization of the outposts fuel regional tension and the United States will continue to sail, fly, and operate anywhere that international law allows.

The deployment of necessary defense facilities on islands and reefs of the Nansha Islands falls under China's sovereignty and the country is exercising its rights of self-protection and self-defense granted by international law, Foreign Ministry spokesperson Hua Chunying said at a regular news briefing.

China has always respected and supported countries in exercising freedom of navigation and flight in the South China Sea in line with international law, Hua said.

She said China firmly opposes countries that threaten and harm the sovereignty and security of coastal countries under the pretext of freedom of navigation and flight.

"Does the United States mean freedom of navigation enjoyed by ordinary ships in line with international law or freedom of intrusion by U.S. military planes and vessels?" she said.

"The United States has repeatedly questioned China's intentions, but will the U.S. explain its real motive in stoking tensions and increasing military presence in the area?" Hua said.

As a non-claimant to the South China Sea, the United States should be discreet with its words and deeds and create a sound atmosphere for directly involved parties to resolve disputes peacefully through negotiation," she said.

"The United States should play a constructive role in regional peace and stability, rather than the opposite," she added.