The US has been claiming its military exercises are for peaceful purposes, which has been doubted by analysts.

U.S. Marines provide security as a U.S. Marine helicopter prepares for landing during a mock helo raid of Exercise Cobra Gold 2011 in Samesan, Thailand, on Feb. 13, 2011. Cobra Gold 2011 marks the 30th anniversary of the exercise, which focuses on basic military skills training, staff planning and humanitarian and civic assistance projects. .[Xinhua/Pr. Photo Cobra Gold 2011]

Judith B. Cefkin, the US deputy chief of mission, said at the opening ceremony of Cobra Gold 2011 that the joint exercise was a symbol of Washington's commitment to supporting the security of its "friends and allies in the Asia-Pacific region".

"The fundamental nature and biggest feature of the joint military exercises lies in its military nature, which cannot be disguised by emphasizing its peaceful purposes," said Senior Colonel Xiao Shizhong from the Academy of Military Science in Beijing.

"Its real purpose is actually to show off its military presence and capacity in the Asia-Pacific region, show its support for nations participating in the exercises, and deter certain nations in this region," said Xiao.

More than 11,000 people, including 7,200 US service personnel, are taking part in the exercises, including ground, air and water drills and 17 humanitarian assistance projects, eight engineering projects and nine medical assistance programs.

China has been sending observers to the exercises since 2002, according to Xiao, refuting Japanese media reports that claim China intends to compete for dominance in security issues in this region.

"It is only groundless speculation by some observers," Xiao said, "due to the nature of such military exercises, China is unlikely to be a participant".

India, Sri Lanka, Laos, Brunei, Russia, Mongolia, South Africa, the United Arab Emirates and New Zealand also sent observers this year, according to the Bangkok Post.