Japan is at a historic crossroads in amending its long-held pacifist defense posture, a move that it may never reverse. Prime Minister Shinzo Abe’s Cabinet formally reinterpreted the war-renouncing Article 9 on Tuesday, reading the Constitution as permitting at least partial use of the right of collective self-defense.

Administration officials and New Komeito lawmakers defend the decision by saying Japan will only use the right under strict conditions.

But many critics, including uncounted numbers of ordinary citizens, doubt the conditions will in reality serve as restraints. They suspect Abe’s aggressive constitutional reinterpretation could eventually allow Japan to wage a war that has far less relevance to the nation’s self-defense.

“What is critical is the fact that it is the government that would judge” whether the self-imposed conditions are met, said Koichi Nakano, a political science professor at Sophia University in Tokyo.

“The administration didn’t even observe the Constitution; it won’t be restrained by the conditions contained in the Cabinet decision,” Nakano said.

Collective self-defense is a right granted to member nations by Article 51 of the United Nations Charter, which allows them to aid allies under military attack. But previous governments have maintained that Article 9 prohibits Japan from exercising that right because it exceeds the “minimum necessary” use of force for self-defense mandated by the war-renouncing Constitution.

Abe maintains that Japan can use “minimum necessary” force in collective self-defense if “there is a clear existential threat to Japan and if people’s right to life, liberty and pursuit of happiness could be fundamentally overturned.”

The ambiguous wording has fanned fears that the government might greatly expand the scope of oversea Japanese military operations to support an ally — most likely the United States — even if Japan itself was not under attack.

Indeed, senior administration officials have suggested that the government could cite the right of collective-self defense in joining a battle, and presumably a war if Japan’s sea lines of communications are threatened — in other words, threats to supplies of oil, gas or food heading to Japan.

Japan’s sea lines of communications for oil imports stretch thousands of kilometers from the Middle East to Tokyo via many potential military flashpoints, including the Persian Gulf, the Indian Ocean, the Strait of Malacca and the South China Sea.

“Overseas supplies of oil, gas, and food are vital interests for Japan. If cut, they would have a huge impact on Japan’s safety and existence,” Abe told an Upper House session on June 9, without elaborating further.

Masahiko Komura, who has chaired the policy discussion for the ruling bloc, declined to comment on what kind of emergency situation along Japan’s sea lines of communication would induce Japan to use the right of collective self-defense. Komura said only “it is impossible to assume” all possible scenarios in advance.

“It depends on how many (supplies) would be cut. . . . (The government) would make a judgment only after something takes place in reality,” Komura said, underlining the ambiguous nature of the conditions set by the Cabinet.

So far, the public has shown mixed reactions to Abe’s drive to expand the scope of Japan’s overseas military operations.

On Monday and Tuesday, hundreds of protesters gathered in front of the prime minister’s office, demanding that Abe step down.

On Sunday, an unidentified man believed to be in his 60s mounted a solitary protest in front of crowds outside JR Shinjuku Station in Tokyo before pouring gasoline on himself and lighting it. The act shocked many people both at home and abroad.

But most Japanese people lack such extremes of feeling about the change, and surveys show a more nuanced assessment.

A poll by the Nihon Keizai Shimbun last weekend found that 50 percent of the 1,029 respondents expressed opposition to the change in interpretation, and only 34 percent supported it. But the same poll showed that the approval rate for Abe’s Cabinet remained unchanged from last month at 53 percent — still impressive compared with other recent Cabinets — while the disapproval rate increased by 4 points to 36 percent.

Japanese people have long known of Abe’s ambition to pull the teeth from Article 9 and make Japan more militarily active.

Still, a majority of people have supported Abe, probably thanks to the tentative success of his aggressive economic and financial policy measures, making him one of the most popular prime ministers in years.

At the same time, many people, in particular the younger generations, support Abe’s drive to expand the role of Japan’s military as collective memories of World War II fade and many Japanese have instead become spooked by China’s rapid military rise.

Until the 1990s, it was an untouchable taboo for any politicians to discuss revising any article of the war-renouncing Constitution.

But now many politicians openly discuss revising the Constitution, including the war-renouncing Article 9, and the pacifist, pro-Constitution Social Democratic Party — once the largest opposition party — has shrunk to a minor party with only five members in the Diet.

Retired Adm. Koichi Furusho, former chief of staff of the Maritime Self-Defense Force, has welcomed Abe’s drive to change the constitutional interpretation, saying Japan may finally be becoming a “normal country,” whose military can engage in missions that are fully accepted under international law, including those involving the use of the right of collective self-defense.

Indeed, Japan is the only country in the world struggling with such legal and technical issues over the right of collective self-defense, which all U.N. member states possess.

“It’s good. It will increase (Japan’s) deterrent power and further improve Japan-U.S. relations,” Furusho said.

He argued that Japan should more actively contribute to international security missions to protect maritime trade cargoes, pointing out that commercial cargo ships transport nearly 1 billion tons of goods to and from Japan every year. Total cargo movements worldwide amount to only 9 billion tons.

“If that (maritime trade) stops, (Japan’s) electricity, gas and even water supplies would halt. Current livelihoods would not be maintained,” Furusho said.