Read more: South China Sea — what you need to know
In a statement, the Defense Ministry announced that the exercise was conducted on a reef, but did not specify where, saying only that it took place at a "southern sea area."
According to the ministry, several H-6Ks carried out simulated strikes against sea targets during the drill.
Wang Mingliang, a military expert, was quoted in the statement as saying that the exercise in the South China Sea will help the Chinese air force "strengthen its combat capability to deal with maritime security threats."
The Washington-based Asia Maritime Transparency Initiative identified the exercise location as Woody Island, China's largest base in the Paracel Islands.
"I believe this is the first time a bomber has landed in the South China Sea," Bonnie Glaser, a China expert at the Center for Strategic and International Studies, tweeted.
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China's maritime 'aggression'The tensions in the South China Sea center on Beijing's claiming virtually all of the sea as its territorial waters, a claim that has been vigorously disputed by Vietnam, the Philippines, Malaysia, Taiwan and Brunei.
The Philippines had been the most vigorous critic of Chinese territorial claims, but President Rodrigo Duterte dialed back his country's objections, leaving Vietnam as the leading critic.
The US has accused China of militarizing the region and redefining its national boundaries to strengthen its claims across the South China Sea. Washington believes China will use the islands and its military presence on them to deny access to strategic sea routes.
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In the Paracel Islands, a new helipad, wind turbines and large radar towers have been built. The radar towers on Triton Island could be used in China's disputes with Vietnam and with the US over freedom of navigation operations, which the US Navy has used to back its perceived right to free passage in international waters.
Earlier this month, China's first domestically built aircraft carrier left dock in the northeastern port of Dalian to begin sea trials of its engine, propulsion and navigation systems. The trials represent a landmark in Beijing's extensive project to modernize its navy as it continues to build up its presence in the disputed South China Sea and around Taiwan, which it sees as its own territory.
Read more: Southeast Asian nations 'want to control China's behavior'
shs/jlw (AFP, AP)