Defense communications between China and Japan were interrupted and bilateral ties became tense after a Chinese trawler collided with Japan Coast Guard ships in September last year near Diaoyu Islands. Despite the untoward development, China responded sympathetically, both at the government and non-government levels, to the March 11 earthquake that devastated Japan, warming bilateral relations.

But Japan's white paper on defense, issued recently, has once again hurt bilateral relations by playing up the "China threat" theory.

The March earthquake and the ensuing tsunami and the Fukushima Daiichi nuclear power plant accident (or triple disaster) have not only hurt the Japanese economy, but also have had a deep impact on its strategic role in the region. Japan has territorial disputes with Russia, the Republic of Korea (ROK) and China, but all the three countries offered aid to it after the quake and tsunami. In spite of that, Tokyo has taken policy decisions under the influence of the US-Japan military alliance and according to its energy demand.

Japan's current foreign policy and the impact of the triple disaster on the Asia-Pacific region's economy and strategic situation will influence international relations in Asia Pacific in the long run.

The US returned to the region last year with its new Asia-Pacific strategy to build a "gooselike security pattern" to tackle China's rise. The US places itself as the leader of Asia Pacific, followed by the US-Japan and US-ROK alliances. The third tier of the US' security ring is its relationship with allies such as Australia, the Philippines and Thailand, and the fourth is its ties with Vietnam, Indonesia and India.

After Japan's triple disaster and Washington's return to the region, the US-led alliance has become more multilateral and expanded its network further. It means that China will face a more united and tighter US-led military alliance in its competition to take the leadership role in East Asian security in the short run.

Besides, the triple disaster will strengthen the asymmetrical US-Japan alliance. Protests and strong opposition in Okinawa, Japan, in 2010 had prevented the Japanese government from signing an agreement with the US on the Futenma Air Station relocation issue. But because of the prompt and large-scale relief provided by the US Forces in Japan (USFJ), Japanese people saw the positive side of US-Japan alliance.

The USFJ's relief work could to a certain extent mitigate Okinawa residents' repulsion against the American military base even though Okinawa prefecture suffered little from the triple disaster, but it cannot altogether quell local people's anger.