U.S. Secretary of Defense Ash Carter kicked off his first Asian tour on Wednesday with a stern warning against the militarization of territorial rows in a region where China is at odds with several nations in the East and South China Seas.
Carter's visit to Japan coincides with growing U.S. concern over China's land reclamation in the Spratly archipelago of the disputed South China Sea, where Beijing has rival claims with several countries including the Philippines and Vietnam.
Tokyo and Beijing have a separate row over Japanese-controlled islets in the East China Sea.
U.S. and Philippine troops will take part in annual military exercises this month near the Spratlys in the largest such drills since the allies resumed joint activities in 2000.
Asked whether the beefed up U.S.-Philippine exercises were a response to China's moves, Carter said Washington and Manila had shared interests in the region, including a desire to ensure there were no changes in the status quo by force or that territorial rows were militarized.
"We take a strong stance against the militarization of these disputes," Carter told a news conference after talks with his Japanese counterpart, Defense Minister Gen Nakatani.
Chinese reclamation work is well advanced on six reefs in the Spratlys, according to recently published satellite photographs and Philippine officials. In addition, Manila has said Chinese dredgers had started reclaiming a seventh.
While the new islands won't overturn U.S. military superiority in the region, Chinese workers are building ports and fuel storage depots as well as possibly two airstrips that experts have said would allow Beijing to project power deep into the maritime heart of Southeast Asia.
The commander of the U.S. Pacific Fleet, Harry Harris, told an Australian think tank last week that China was using dredges and bulldozers to create a "great wall of sand" in the South China Sea.
China claims most of the potentially energy rich waterway, through which $5 trillion in ship-borne trade passes every year. The Philippines, Vietnam, Malaysia, Brunei and Taiwan also have overlapping claims.
Tighter alliance ties
Carter also welcomed progress toward the first update in U.S.-Japan defense cooperation guidelines since 1997, a revision that will expand the scope for interaction between the allies in line with Prime Minister Shinzo Abe's push to ease the constraints of Japan's pacifist constitution on the nation's military.
"It's going to give first of all Japan, but also our alliance, much greater scope to provide security in the region, and for that matter elsewhere outside of the region," Carter said as the talks began.
Abe's move to allow Tokyo to come to the aid of an ally under attack would pave the way for closer cooperation between U.S. and Japanese forces across Asia, Admiral Robert Thomas, commander of the U.S. Seventh Fleet, said last month.
In January, Thomas said the United States would also welcome Japanese air patrols in the South China Sea.
Nakatani told the news conference with Carter, however, that the new guidelines did not target any particular region including the South China Sea.
Neither Tokyo nor Washington have territorial claims in the South China Sea, but the U.S. Seventh Fleet operates in the area and any Japanese presence would irritate Beijing.
In a written interview with Japan's Yomiuri newspaper published on Wednesday, Carter expressed concern about China's land reclamation in the South China Sea.
"We are especially concerned at the prospect of militarization of these outposts. These activities seriously increase tensions and reduce prospects for diplomatic solutions," the newspaper quoted him as saying.
"We urge China to limit its activities and exercise restraint to improve regional trust."
Carter also repeated Washington's opposition to any "coercive unilateral" actions by China to undermine Japan's administrative control of disputed islands in the East China Sea, known as the Senkaku in Japan and the Diaoyu in China.
China's Foreign Ministry spokeswoman Hua Chunying told a regular news briefing in Beijing: "We hope the U.S. side can respect the wishes of China and relevant countries to resolve the problem via dialogue, say more responsible things and make more responsible moves, so it can genuinely play a constructive role in maintaining regional peace and stability."
Abe's government plans to submit bills to parliament in the coming months to ratify his cabinet's decision last year to allow Japan to exercise its right of collective self-defense, the biggest shift in Japanese security policy in decades.
Carter, Nakatani and the two countries' foreign ministers are expected to unveil the new defense guidelines in late April, before Abe meets U.S. President Barack Obama on April 28 for a summit in Washington.