Washington and Tokyo kicked off a military drill, which envisioned retaking an island, in what analysts said was a clear signal that the US was throwing its military weight behind Japan over the Diaoyu Islands issue.
The 37-day drill, which started on Tuesday, involves troops sailing 2,000 km on a US vessel to Tinian Island, off the coast of the Northern Marianas. Boats and helicopters will then be deployed in a joint landing.
Although no country was named as the target of the exercise, an official with the Japanese Defense Ministry indicated that the drill is obviously devised to "seize back" the Diaoyu Islands "once China’s armed forces have taken them", according to a report by Japanese newspaper Sankei Shimbun.
The timing of the drill, and Washington’s involvement, will complicate the situation, analysts said. The Diaoyu Islands have belonged to China for centuries and this is not the first time that the US has been involved.
At the end of its occupation of Okinawa in 1972, the US transferred the "administrative rights" of the Diaoyu Islands to Japan. They had been occupied by Japan until its defeat at the end of World War II in 1945 and were then "administered" by the US. China has never recognized the deal "giving" them to Japan.
Washington remains neutral on the issue, but it "falls within Article 5 of the US-Japan Security Treaty", US State Department spokeswoman Victoria Nuland said on Thursday.
Li Hong, secretary-general of the China Arms Control and Disarmament Association, said the US-led drill is increasing tension in the region and has shown Washington’s true colors despite its so-called neutral stance over the issue.
Wang Fan, director of the Institute of International Relations at the China Foreign Affairs University, said the drills "will only escalate Tokyo’s tensions with its neighbors, instead of helping resolve them".
Ties between China and Japan have been strained by Tokyo’s stance on the Diaoyu Islands since 2010 when a Chinese trawler captain was held by Japanese authorities for what Japanese called "illegal fishing" off the islands.
The ruling Democratic Party of Japan has used the Diaoyu Islands issue to boost wavering public support, experts said.
Japanese Prime Minister Yoshihiko Noda announced in July his cabinet’s plan to "nationalize" the islands, sparking protests from China.
"Tokyo is keen to use the drills to signal that Washington is on its side," said Ni Feng, a researcher of American Studies at the Chinese Academy of Social Sciences.
The last week has seen Chinese activists and Japanese nationalists land on the islands.
Tsuyoshi Yamaguchi, parliamentary senior vice-minister of foreign affairs, is scheduled to visit Beijing this week, and analysts said the Diaoyu Islands dispute will be on his agenda.
Tokyo’s top lawmakers on Tuesday indicated a possible revision of laws to boost territorial surveillance "in Japanese waters".
After announcing its shift of strategic emphasis back to the Asia-Pacific region, Washington is using the Diaoyu Islands issue as a chance to speed up its military revamp in the region, observers said.
The US and Japan agreed earlier this month on a proposed second revision of the Guidelines for Japan-US Defense Cooperation, a move believed to target China.
Washington has held a series of drills with its allies this year, including the US-Japan-Republic of Korea drill in June and the Rim of the Pacific Drills 2012 that ended earlier this month. The US and Japan on Sunday held a joint exercise in Ooitaken, southwestern Japan.
Dragging Japan into its Asia-Pacific plans makes no sense for the US regarding a resolution of the territorial issue, Li said.
"China will never concede on territorial issues," Li said.