Experts said that if Washington continues to flex its military muscles in the South China Sea, it may prompt China to boost its defense buildup there to safeguard its lawful rights.

That observation was made in response to a series of incursions US naval warships have made into Chinese territorial waters in the South China Sea in the name of "Freedom of Navigation".

Foreign Ministry spokesman Hong Lei said on Friday that the US "has consistently strengthened its military buildup in the South China Sea", and it has lured or pressured its allies or partners to embark on joint military drills in the South China Sea.

"Such actions have worsened the tense situation in the South China Sea and are acts of boosting 'militarization'," Hong said.

Hong made the comments in answer to US State Department spokesman John Kirby's claim that the US sees no indication that China's "militarization effort" has stopped.

Hong added that China has deployed defenses on Yongxing in the Xisha Islands in the South China Sea since 1959.

Jin Canrong, a professor of international relations at Renmin University of China in Beijing, said if Washington continues to flex its military muscle in the South China Sea, "China would be forced to boost its defense capacities there".

"One could conceive of Washington motivating countries to get into a dispute with China to challenge China militarily. That could lead to a security dilemma and a vicious circle in which both sides would race to boost their military buildup," Jin said.

Ruan Zongze, vice-president of the China Institute of International Studies, said that China should further fortify its defense facilities there "in accordance with the degree of the threats posed".

"International law gives sovereign states the right to self-preservation and self-defense," Ruan said.

In another development, Beijing has urged the US to "act cautiously, and not cause trouble artificially" when addressing the Korean Peninsula issue, as the US administration approved new sanctions against the Democratic People's Republic of Korea.

"Any behavior that harms the interests of a third party won't help address the issues, but only further complicate the situation," ministry spokesman Hong said.

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