SINGAPORE -- Two large artillery vehicles were detected on one of the artificial islands that China is creating in the South China Sea, U.S. officials said Friday, underscoring ongoing concerns that Beijing may try to use the land reclamation projects for military purposes.
The discovery was made at least several weeks ago by the United States, but it's not clear if the weapons are still there or if they have been moved or hidden out of sight, officials said.
The revelation comes as Defense Secretary Ash Carter begins an 11-day trip, including several stops in the Asia Pacific. He is slated to speak Saturday at an international security summit here, and is expected to reassert America's views that China and other nations must stop all land reclamation projects in the region.
Pentagon spokesman Brent Colburn said the U.S. was aware of the artillery , but he declined to provide other details, saying it is an intelligence matter. Defense officials described the weapons as self-propelled artillery vehicles, and said they posed no threat to the U.S. or American territories. The officials were not authorized to discuss the matter publicly so spoke on condition of anonymity.
The sighting was first reported by the Wall Street Journal.
U.S. officials, however, have been watching the rapidly expanding land reclamation by China, which, according to estimates, totals more than 2,000 acres in the South China Sea.
Carter on Wednesday made it clear that the U.S. will "fly, sail and operate wherever international law allows." But so far he has said little about what the U.S. is willing to do to get China to stop the island construction.
U.S. and other regional officials have expressed concerns about the island building, including worries that it may be a prelude to navigation restrictions or the enforcement of a possible air defense identification zone over the South China Sea. China declared such a zone over disputed Japanese-held islands in the East China Sea in 2013.
Asked about the latest imagery suggesting China had put weapons on one of the land reclamation islands, China's Foreign Ministry spokeswoman Hua Chunying said she is "not aware of the situation you mention, but China has clearly reiterated its position several times on the islands in the South China Sea."
She also pushed back against Carter's criticism, saying that the U.S. should be "rational and calm and stop making any provocative remarks, because such remarks not only do not help ease the controversies in the South China Sea, but they also will aggravate the regional peace and stability."
Carter has been vocal about U.S. opposition to the China construction and on Friday afternoon flew over the crowded Straits of Malacca and Singapore, in part to emphasize the need for continued freedom of navigation in the region.
On board two V-22 Ospreys, Carter and his staff and several members of the media flew over the narrow shipping lanes, which were packed with massive container ships and other vessels.
The busy waterway is "a very striking example of the link between security and prosperity and the importance of having security and stability in the Pacific," said Kelly Magsamen, the Pentagon's principle deputy assistant secretary for Asia Pacific matters.
Colburn, the Pentagon spokesman, added that China's actions in the South China Sea are examples of the types of things that could extend into otherAsia Pacific areas and "could upset the order that has led to the prosperity that the entire region benefits from today."
The Malacca Strait is 550 miles long, but just 1.7 miles wide at its narrowest point. About a third of global shipping moves through the strait -- or about 50,000 ships a year. Any accidental or deliberate blockage of the strait would force ships to switch to longer and more expensive routes.
-- AP news assistant Liu Zheng in Beijing contributed to this report.