TOKYO — When the U.S. ambassador to Japan met with the head of that nation’s leading opposition party last month, he had more than diplomatic courtesy on his mind. Ambassador Thomas Schieffer was eager to enlist the Democratic Party of Japan’s assistance in renewing an anti-terrorism law that would effectively continue Japan’s involvement in the war in Afghanistan.

The meeting might never have occurred at all had the DPJ not scored a major coup in national elections held in July by winning control of Japan’s upper house of Parliament for the first time. The victory divided Japan’s legislature and made the DPJ’s combative boss, Ichiro Ozawa, an instant power broker, much to the consternation of Bush administration officials such as Schieffer, who had not met with Ozawa in the two years since he moved to Tokyo as the U.S. envoy.

Ozawa was not about to forget past slights. Brushing off post-electoral congratulations, Ozawa publicly rebuked Schieffer — in front of the assembled Japanese media — and vowed to use his party’s new power to kill the anti-terrorism bill. “The U.S. started this war unilaterally without waiting for a consensus to be built in the international community,” he declared.

The incident marked the beginning of what experts predict will be a tumultuous new period in Japanese politics. With the Parliament divided and Liberal Democratic Prime Minister Shinzo Abe politically weakened, the Ozawa-led opposition is expected to begin using defense and foreign policy issues to draw into question Abe’s image as a capable steward of international affairs. The goal, experts say, is to provoke a crisis that would force Abe to dissolve the lower house that his party, the LDP, still controls and call for early elections.

A shift in what has long been a cordial relationship between the U.S. and Japanese governments could be another effect. “Ozawa wanted to make a big show, and Schieffer played directly into his hands” by bringing up an issue that allowed the DPJ leader to set himself apart from the ruling party, said Yukio Okamoto, an adviser to the previous prime minister, Junichiro Koizumi.

U.S. officials will be closely watching developments next week, when the Diet, or parliament, meets for the first time since the elections. “We hope that the political debate here will not wind up making the U.S.-Japan alliance a political football,” Schieffer told Japanese reporters after the public dressing-down. But Okamoto says the United States could unwittingly help Ozawa’s cause by insisting that Japan continue a longstanding practice of deferring to U.S. wishes, especially in the Bush administration’s efforts to combat global terrorism and bring stability to Iraq.

Most experts believe the foundation of the U.S.-Japan relationship remains sound and that whichever party is in charge in Tokyo will ultimately put national security over politics. But right now Japanese politics is changing quickly, these experts say, and the U.S. is paying the price for failing to engage the opposition early on.

Many refer to the Bush-Koizumi period as the “Golden Age” of the alliance. The pair shared conservative positions and enjoyed a close personal friendship.

In contrast, Ozawa is poised to exploit growing dissatisfaction in the Japanese public with Bush administration policies in several areas, hoping to block some collaborative defense pacts and generally depict the ruling party as too eager to accommodate Washington. He also will try to tap intensifying sentiment among the electorate that Japan needs to evolve into a more independent and assertive nation.

“Japan is in for a period of a very difficult, bad political season,” said Gerald Curtis, professor of Japanese politics at Columbia University. “You’re going to have a period of political uncertainty and policy paralysis.”

Ozawa rocked Japan’s political establishment in July by handing the ruling Liberal Democrats their worst electoral defeat since the party was formed in 1955, said Curtis. Though the DPJ took 39.5 percent of the vote and won 60 of 121 contested seats in the House of Councillors, the Diet’s upper chamber, most experts agree that result was not an endorsement of the opposition but rather an expression of discontent with the ruling party and the prime minister.

The Abe administration was hurt by the revelation that the government mishandled over 50 million pension accounts. Unrelated financial scandals had led three Cabinet ministers to resign and one to commit suicide. And rural voters, the LDP’s core constituency, abandoned the party to protest their declining economic standing and their objections to free-market economic reforms.

Ozawa, a native of rural Iwate prefecture, appealed directly to this voting bloc. Defense and foreign policy were not a prominent part of the campaign debate.

Though Ozawa has no formal title in the new government, he is poised to dictate the upper house’s agenda — and play spoiler by shooting down legislation to thwart the ruling coalition’s agenda.

Three areas of U.S.-Japan defense cooperation could become early battlegrounds. First, if Ozawa upholds his promise to block renewal of an anti-terrorism law that’s set to expire Nov. 1, Japan would have to stop maintaining its ships in the Indian Ocean that have been providing fuel and other logistical support for U.S.-led coalition ships involved in operations in Afghanistan.

On a visit to Japan last month, the outgoing chairman of the Joint Chiefs of Staff, Gen. Peter Pace of the Marines, said the Pakistani navy in particular is dependent on the Japanese fuel, making it “not impossible, but very difficult” to replace Japan’s support.

The DPJ could also stifle Abe’s efforts to lift a Japanese constitutional ban on “collective defense” — joint operations with foreign militaries — which would enable Japanese forces to operate more jointly with the American military. A Japanese advisory board may recommend lifting the ban in a report due this fall, but without DPJ support, experts say, Abe won’t have the clout to make the change.

Lastly, the DPJ is weighing whether to introduce legislation that would recall the Japanese air defense forces based in Kuwait, the country’s only contribution to the international forces supporting the war in Iraq. These planes have represented Japan’s sole involvement in the war since the country last year pulled out more than 600 non-combat troops that served a support role on the ground in the Iraqi city of Samawah since 2004.

Ozawa probably believes that his opposition to the anti-terrorism law and his anti-U.S. rhetoric will play well with the majority of Japanese voters. Recent polls support this theory.

According to an August survey by the Japanese newspaper The Asahi Shimbun, 53 percent of Japanese polled oppose extension of the law, while only 35 percent support it.

A March poll by the newspaper revealed widespread Japanese skepticism of U.S. foreign policy. Three-quarters of those surveyed agreed with the statement that the U.S.-led war in Iraq was not justified. Only 24 percent thought that the global war on terrorism would deter attacks throughout the world. And while 69 percent said the Japanese government should take a hard look at its cooperation with the United States, only 18 percent supported leaving the relationship as is.

The unpopularity of the Bush administration and the Iraq War is making it much more difficult for the Japanese government to persuade the people to go along with U.S. initiatives, according to Koji Murata, a professor at Kyoto’s Doshisha University and a popular conservative commentator.

Further complicating matters is a recent shift in the U.S. stand toward North Korea that has shocked the Japanese public. Since 2002, the United States and Japan have held a hard line in negotiations with Pyongyang, while China and South Korea have been more conciliatory. But in February, the administration granted concessions, including agreeing to allow the release of $25 million of North Korean funds that had been frozen in a Macau bank in 2005 as part of a money-laundering investigation. In return, North Korea has resumed allowing international monitoring of its nuclear program and has begun to shut down a nuclear reactor at Yongbyon.

The thawing of relations didn’t go over well with Japanese, who have made a priority of resolving the abduction of Japanese citizens by the North Korean government in the 1970s and 1980s. North Korea has returned five of the 13 abductees that it has acknowledged kidnapping, but the Japanese suspect that North Korea has lied about the fate of eight others and that many more abductions remain unrevealed.

As a likely target of North Korean missiles, Japanese also are sensitive about being excluded from U.S. decisions regarding the crisis. “For many Japanese people, it seems like a betrayal,” said Murata, “They may think, ‘It’s unfair, while we are helping them, they are not helping us.’ ”

Should Ozawa succeed in his long-term strategy and make the DPJ the ruling party, conventional wisdom holds that U.S. interests would be harmed. The party’s manifesto says the Iraq War “lacks justification” and criticizes Liberal Democrats for failing to consult with the Japanese communities where U.S. military bases are located.

But the DPJ is in fact an extremely diverse party, making it unclear just how it would address security and foreign relations.

The party itself is a loose conglomeration of former LDP conservatives, such as Ozawa, former members of the now defunct Socialist Party, and a younger group of lawmakers who call themselves the “born free Democrats” because they began their careers in the party and don’t have any lingering allegiances.

Parliament member Akihisa Nagashima, defense minister in the DPJ’s “shadow Cabinet,” is confident that conservative, young members of the party have enough clout to control the party’s security policy should they be put into power. Nagashima says Ozawa is criticizing Japan’s handling of the U.S.-Japan alliance because that is the role of an opposition leader. “Ozawa simply uses that logic; he doesn’t have any real alternative. If we take power, we will have to do almost the same things as what the ruling party does now.”

Nagashima and other young party leaders worry that the DPJ could be viewed as blocking legislation such as the anti-terrorism bill for the sake of it, adding, “We have to demonstrate we are capable using the upper house position.”

The U.S.-Japan relationship is an easy target for political rhetoric, Nagashima said, adding that diplomacy must have consistency, and that DPJ leaders know that Japan must balance rising nationalism with national security considerations.

There will be adjustments in Japan’s approach to the alliance under a DPJ administration, Nagashima said. Koizumi and Abe cooperated blindly with the U.S., but that will need to change. “No alliance is equal, but you have to make an effort towards symmetry,” he said.

In fact, some analysts say a DPJ government might be more favorable to the United States’ new efforts to engage North Korea. The DPJ has been encouraging the Japanese government to improve ties with China and South Korea.

Many Japanese experts caution that the United States will have to walk a fine line as Japan sorts through its political growing pains and gets accustomed to divided government. Okamoto says U.S. officials should avoid appearing to openly pressure Ozawa to bend their way and further inflame anti-U.S. sentiment.

Robert Dujarric, director of Contemporary Japanese Studies at Temple University Japan, predicts that the row over the anti-terror law and foreign policy will subside and that the political focus in Japan will gradually return to domestic issues. He adds that the real legacy of the recent election will be felt in the economic arena, because of an influx of new legislators who oppose free-market reforms and are less likely to support deregulation and proposed cuts to the government’s generous subsidies for farming and construction. That development could complicate future trade negotiations and discourage foreign investment, he said.

Regardless of which party comes out on top, analysts warn that a more assertive, independent-minded Japan is a reality that future U.S. administrations will have to contend with, and should not necessarily be viewed as a bad thing.

“A ‘normal’ Japan, long desired by Washington, is also a Japan at liberty to say no,” said Tobias Harris, a Tokyo-based Japan analyst.

Bush and North Korea, CQ Weekly, p. 726; U.S.-Japanese trade, p. 645.