TOKYO — U.S.-Japan relations are in "crisis," Japan's foreign minister told me Thursday — but I would guess that few Americans have noticed, let alone felt alarm. As China rises, Japan's economy has stalled, and its population is dwindling.

But Japan still matters. And despite the "crisis" set in motion by the electoral defeat of the party that had ruled for half a century, the United States has more to fear from Japanese defeatism — from its own uncertainty about whether it still matters — than from the assertiveness of its new government.

At a seminar here last week organized by the German Marshall Fund and the Tokyo Foundation, and in separate interviews, one Japanese after another delivered variations on gloom, doom and pessimism. Polls confirm that this is no anomaly; in one taken by the Asahi Shimbun newspaper last spring, the three words offered most often to describe the current era were "unrest," "stagnation" and "bleak," as the paper's editor in chief, Yoichi Funabashi, noted recently in Foreign Affairs.

Japan's fiscal challenges are daunting, as is its declining birthrate. Yet the negativity seems overblown. Japan retains the world's second-largest national economy and will be third or fourth biggest for decades to come. It is the world's second-largest aid donor, the fifth-biggest military spender (despite a constitution that bars the waging of war) and a technological powerhouse. It is a crucial player, and frequently America's closest ally, in international organizations such as the World Bank and the International Monetary Fund. And as the longest-standing and most successful democracy in the non-Western world, it is a hugely important role model, and potentially a leader, in supporting freedom and the rule of law.

That potential was sharply enhanced by the landslide victory of the Democratic Party of Japan in August, ending what one speaker at the seminar called the Liberal Democratic "shogunate." The Democrats have promised to disrupt the cozy relationship among bureaucrats, the ruling party and industry, and to govern with more public input and accountability.

But they're also disrupting the U.S.-Japan relationship. An agreement to realign U.S. Marine bases in Okinawa has been put on hold, despite what U.S. officials took as a promise from Prime Minister Yukio Hatoyama to implement the deal. The Democrats' coalition partners, as well as voters in Okinawa, loathe the pact.

"So we are in a situation where the U.S.-Japan alliance is being tested," Foreign Minister Katsuya Okada acknowledged.

Democratic Party officials have said they want to put the U.S.-Japan relationship on more equal footing, and Hatoyama and others have at times gone further, suggesting a desire to improve relations with China while downgrading those with the United States. But Okada dismissed suggestions that the suspension of the base agreement reflects a deeper-seated resentment of America or a fundamental questioning of the alliance.

Citing North Korea's nuclear weapons and China's growing military, Okada said, "I don't think anyone would think that Japan on its own can face up to such risks. That is why we need the U.S.-Japan alliance. I don't think any decent politician would doubt that as a fact."

Frustrated by Hatoyama's amateurish handling of the issue, Obama administration officials are scrambling to come up with the right mix of tolerance for the coalition's inexperience and firmness on implementing an agreed-upon deal. They're right to insist on the importance of the military alliance, long a force for stability throughout the region.

But they shouldn't lose sight of the larger picture. For years now the United States has been trying to engage China's government in strategic dialogues and high-level commissions. It should do no less with Japan, its most important democratic ally in Asia, and the advent of an untested government still feeling its way provides both reason and opportunity to do so.

So far, Japan's new government has not defined policies that could restore economic growth and lift the country out of its funk. But America should be hoping that it can. And if it wants Japan to regain some confidence, it makes sense to treat Japan as though it matters. Because it does.