SINGAPORE — China's land reclamation in the South China Sea is out of step with international rules, and turning underwater land into airfields won't expand its sovereignty, Defense Secretary Ash Carter told an international security conference Saturday, stepping up America's condemnation of the communist giant as Beijing officials sat in the audience.
Carter told the room full of Asia-Pacific leaders and experts that the U.S. opposes "any further militarization" of the disputed lands. His remarks were immediately slammed as "groundless and not constructive" by a Chinese military officer in the audience.
Carter's comments came as defense officials revealed that China had put two large artillery vehicles on one of the artificial islands it is creating in the South China Sea. The discovery, made at least several weeks ago, fuels fears in the U.S and across the Asia-Pacific that China will try to use the land reclamation projects for military purposes.
The weaponry was discovered at least several weeks ago, and two U.S. officials who are familiar with intelligence about the vehicles say they have been removed. The officials weren't authorized to discuss the intelligence and spoke only on condition of anonymity.
The Pentagon would not release any photos to support its contention that the vehicles were there.
China's assertive behavior in the South China Sea has become an increasingly sore point in relations with the United States, even as President Barack Obama and China's President Xi Jinping have sought to deepen cooperation in other areas, such as climate change.
Pentagon spokesman Brent Colburn said the U.S. was aware of the artillery, but he declined to provide other details. Defense officials described the weapons as self-propelled artillery vehicles and said they posed no threat to the U.S. or American territories.
While Carter did not refer directly to the weapons in his speech, he told the audience that now is the time for a diplomatic solution to the territorial disputes because "we all know there is no military solution."
"Turning an underwater rock into an airfield simply does not afford the rights of sovereignty or permit restrictions on international air or maritime transit," Carter told the audience at the International Institute for Strategic Studies summit.
This article first appeared on NBCNews.com.