“China does not intend to pursue militarization,” Mr. Xi said, referring to the area as the Nansha Islands, a Chinese name for what most of the rest of the world calls the Spratlys in the South China Sea.
The most recent satellite photographs suggest a different plan. The photos, collected and scrutinized by the Center for Strategic and International Studies, a Washington-based research organization, show the construction of what appear to be reinforced aircraft hangars at Fiery Cross, Subi and Mischief Reefs, all part of the disputed territories.
There were no military aircraft seen at the time the photos were taken. But a summary of the center’s analysis suggests that the hangars on all three islets have room for “any fighter-jet in the People’s Liberation Army Air Force.”
A larger type of hangar on the islets can accommodate China’s H-6 bomber and H-6U refueling tanker, a Y-8 transport aircraft and a KJ200 Airborne Warning and Control System plane, the center said in its analysis.
While China may assert that the structures are for civilian aircraft or other nonmilitary functions, the center says its satellite photos strongly suggest otherwise. Besides their size — the smallest hangars are 60 to 70 feet wide, more than enough to accommodate China’s largest fighter jets — all show signs of structural strengthening.
“They are far thicker than you would build for any civilian purpose,” Gregory B. Poling, director of the center’s Asia Maritime Transparency Initiative, said on Monday in a telephone interview. “They’re reinforced to take a strike.”
The largest hangars, 200 feet wide, are “more than enough for strategic bombers and refuelers,” Mr. Poling said.
If those planes were deployed, they would greatly complicate China’s disputes with the Philippines and other nations, and add a level of military risk to the United States’s “freedom of navigation” patrols through the area.
Even before the hangars appeared, it was clear to independent military analysts that China’s intention was to use the islands to flex military might in the area.
“We knew from the day they started building those runways,” Mr. Poling said. For China to assert a more benign purpose, he said, would be “like saying you’re building a mansion, but only living on the first floor.”
Evidence of the military hangars emerged a month after an international tribunal at The Hague sharply rebuked China over its behavior in the South China Sea, including its assertion of expansive sovereignty and construction of artificial islands.
The tribunal’s ruling was a response to a landmark case brought by the Philippines, which called it an “overwhelming victory.” Infuriated, China said it would ignore the ruling.
Some analysts cautioned that the hangars were not a response to the ruling and had likely been under construction for some time.
“The foundations may have been laid months ago,” said M. Taylor Fravel, a political science professor at the Massachusetts Institute of Technology and a member of its Security Studies Program.
Mr. Fravel said the hangars are not necessarily inconsistent with the Chinese president’s assertions.
“China has given itself the option to use these reefs as military facilities, but has not decided yet to what degree it is going to use them,” he said. “It creates the option for a robust defense of those places or even a power projection.”