With U.S. military forces stretched across the globe, it's reassuring to see one of America's best allies chipping in and laying foundations for shouldering more of the burden. And no, we're not talking about Britain. We're referring to Japan.

Yesterday, the lower house of the Diet passed a bill to extend, for two years, Japan's commitment to provide air support for U.S.-led forces in Iraq. Given the ruling Liberal Democratic Party's majority in the upper house, it's likely the bill will soon become law.

This kind of support is becoming par for the course for Japan, which has extended billions in development aid and reconstruction help to Iraq and neighboring countries. Explaining yesterday's vote, Prime Minister Shinzo Abe noted that Japan "imports nearly 90% of its petroleum resources from the Middle East, including Iraq."

In other words, Japan's national interests are aligned with those of West to promote peace in the Middle East and stop terrorism. But the difference is that, unlike some Western European countries, Tokyo is risking both capital and people to do so. Not only are Japanese forces flying missions in Iraq, but their maritime forces have spent the past six years working in the Indian Ocean, providing support for the troops in Afghanistan.

That's about all the help Japan can legally provide until it changes its pacifist constitution. On Monday, the upper house passed legislation outlining a legal framework to do just that. The referendum law, which takes effect in 2010, stipulates that the Diet must pass any constitutional referendum with a two-thirds majority and then put it to the people for a vote. Voters would have to ratify the referendum by a simple majority to make it law.

Some of Japan's East Asian neighbors are treating the news as if Japan is back to its World War II mindset; a spokesman for South Korea's conservative Grand National Party told Yonhap News Agency that "we have serious concerns that Japan will be able to possess a military and that could lead to the revival of its imperial militarism."

That's a heady exaggeration. Mr. Abe has repeatedly spoken of "normalizing" Japan's role in foreign affairs, but he also understands that he's constrained by public opinion, which, for now, seems evenly split on constitutional reform. Though the referendum bill passed the lower house easily last month, it didn't receive a two-thirds majority in the upper house on Monday. So if Mr. Abe tried to pass constitutional reform today, the measure wouldn't even make it out of the Diet.

Meanwhile, the military threats Japan faces are imminent and growing. North Korea is now nuclear capable, and China continues to ramp up its air, land and sea forces. Given that background, it's prudent for Mr. Abe to lay the foundation for a national debate on constitutional change.

Which brings us back to Iraq. Mr. Abe explained yesterday that keeping troops on the ready there is necessary because "reconstruction and stability in Iraq" still isn't complete. That decision isn't popular with many in Japan, but Mr. Abe seems to understand that responsible leadership sometimes means not pleasing everyone. Some politicians in Washington could take note.

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