TOKYO Japan has the right to develop the ability to make a pre-emptive strike against an imminent attack given a changing security environment although it has no plan to do so now, the defence minister said on Thursday, days after North Korea conducted a third nuclear test.
Any sign that Japan was moving to develop such a capability in response to North Korea's nuclear programme could upset neighbours China and South Korea, which have reacted strongly in the past to suggestions it might do so.
"When an intention to attack Japan is evident, the threat is imminent, and there are no other options, Japan is allowed under the law to carry out strikes against enemy targets," Defence Minister Itsunori Onodera told Reuters in an interview.
"Given Japan's political environment and the peace-oriented diplomacy it has observed, this is not the time to make preparations (for building such capability).
"But we need to carefully observe the changing security environment in the region."
North Korea conducted its third nuclear test on Tuesday, drawing condemnation from the United States, Japan, Europe and the North's only major ally, China.
Onodera said Japan needed to strengthen its ballistic missile defence in view of the North Korean threat.
"Japan, the United States and South Korea managed to respond well to North Korea's missile launch on December 12. But North Korea is expected to boost various capabilities further. We need to improve corresponding capabilities as well."
But he declined to say whether it was more urgent than ever to lift a self-imposed ban on exercising the right of collective self-defence, or coming to the aid of an ally under attack.
Exercising that right is now prohibited under a long-standing interpretation of Japan's pacifist constitution but Prime Minister Shinzo Abe has made clear he wants to lift the ban and a panel of advisers has begun discussing the topic.
Onodera called on China to join the United States, Japan and other countries in tightening sanctions against North Korea, noting that Pyongyang had gone ahead with the test on Tuesday in defiance of Beijing's urging not to.
"I think China is the one that is most concerned about the development ... From now on, it is necessary for us, including China, to seek effective steps, effective economic measures (against North Korea)."
Onodera urged China to work with Japan to set up hotline and other communications channels between Tokyo and Beijing to prevent any accidental clash over disputed East China Sea islets, while reiterating that the islands belonged to Japan.
Sino-Japanese ties cooled sharply after Japan's government in September nationalised three of the disputed islets, called the Senkaku in Japan and Diaoyu in China.
The island row has escalated to the point where both sides have scrambled fighter jets while patrol ships shadow each other, raising worries that an unintended collision or other incident could lead to a broader clash.
"There already is a preliminary agreement between Japan and China to set up a maritime communication mechanism," Onodera said.
"The mechanism would include annual meetings, specialists' meetings, hotlines between high-ranking people, and direct communications between ships and planes in the field. I would like to have final agreement reached as soon as possible."
Onodera said last week a Chinese frigate had locked its targeting radar on a Japanese destroyer on January 30 - a step that usually precedes the firing of weapons - but China insisted that its vessel used only ordinary surveillance radar.
He said in the interview that Japan has data to back up its assertion, but was cautious about disclosing the information.
"We have irrefutable data. But (disclosure) would also reveal our various capabilities. We would like to discuss (possible disclosure) within the government, while watching China's future steps."
(This story corrects the date of nuclear test to Tuesday from Monday in paragraph 11)