Hours after the Islamic State group published on social media on Saturday a videotape purported to show the beheading of its second Japanese hostage, journalist Kenji Goto, the Japanese government expressed “extreme indignation" for the "deplorable terrorist act." Prime Minister Shinzo Abe said on TV he felt "very sorry" and that "the government has tried its best" to secure the release of the hostage. The group also known as ISIS initially demanded a $200 million ransom and, after the first of its Japanese hostages was beheaded, also demanded the release of a convicted suicide bomber being held in Jordan.

Chief Cabinet Secretary Yoshihide Suga said the government was convening an emergency meeting. Japan, whose military is constitutionally barred from offensive action, has no ability to respond immediately with armed force to the killing of Goto and the other Japanese victim, Haruna Yukawa.   

But Abe himself is spearheading a drive to scrap the constitutional ban, stemming from Japan's defeat in World War II. The killings of two Japanese citizens may push public opinion, so far against scrapping the ban, more to his side.

Japan formally renounced in 1947 its right to wage war and to have armed forces. It does in fact have an army, a navy and an air force, which it calls self-defense forces to avoid the appearance it could use them to fight a war. But its ground soldiers, ships and aircraft all possess offensive weapons. Japanese military forces have not fired in anger since World War II, but they do have the theoretical capability to take part in action against ISIS.

Article 9 of the postwar Constitution, titled "Renunciation of War," reads: "Aspiring sincerely to an international peace based on justice and order, the Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as a means of settling international disputes. To accomplish the aim of the preceding paragraph, land, sea and air forces, as well as other war potential, will never be maintained. The right of belligerency of the state will not be recognized." 

In July 2014, Abe pushed through an executive resolution from the cabinet that, while leaving Article 9 untouched, introduced the possibility Japan could fight if it is threatened. The three conditions that must be met, according to the resolution, are that there is a threat to the existence of the Japanese state, that there is a clear danger to its people's right to life, liberty and the pursuit of happiness, and there is no appropriate alternative.

"There is no change in the general principle that we cannot send troops overseas," Abe said last year after the resolution passed. And earlier this month, during a press conference involving the kidnapping crisis, he reiterated, "There  are three conditions for exercising self-defense." The Islamic State group, while undoubtedly a threat, hardly endangers the survival of the faraway Japanese nation. Still, Abe added, "In any event, Japan needs to get its security laws in order to ensure smooth and unpunctuated countermeasures,” a reference that may indicate his willingness to pursue constitutional reform.

In a 2013 interview with Foreign Affairs magazine, the conservative Abe said the Japanese public would support moving beyond Article 9, if people saw a reason to do so.

“Only 30 percent of the people support enabling the right to use force for collective self-defense,” he said. But in case of, for example, an aggressive act from North Korea, "then more than 60 percent of the public acknowledges that this is not right,” Abe said.

There is no polling available yet on the opinion of the Japanese public about changing the constitution in the wake of the twin beheadings. Experts are unsure even the resolution passed last year was permissible. "It was entirely illegitimate and poses dangers to Japan’s democracy," Craig Martin, a professor at Washburn University and expert on Japan who graduated from Osaka University, wrote last year.

In any case, Japan lacks at this point the weaponry it would need to take any meaningful part in the U.S.-led campaign of airstrikes against ISIS. Its warplanes, while advanced and very capable, are meant to be used for defense against enemy aircraft and have limited ability to bomb ground targets. It would not be easy, or useful in military terms, to integrate the Japanese air force in the airstrike campaign, even if it were legal.

"The vast majority of the Japanese are still reluctant to amend article 9," Martin said in a phone interview. "First (Abe) may try to amend article 96. That will take time and is a difficult process." Article 96 specifies the procedure for amending the constitution, requiring a special majority in parliament plus a referendum: "Amendment to this Constitution shall be initiated by the Diet, through a concurring vote of two-thirds or more of all the members of each House and shall thereupon be submitted to the people for ratification which shall require the affirmative vote of a majority of all votes cast thereon, at special referendum or at such election as the Diet shall specify."  

"Any deployment of the Self-Defense Forces would require a law," Martin said. "If they try to deploy forces in the absence of legislation they would run into massive opposition, and there could be legal challenges." In the meantime, according to Martin, "the government is in a difficult position. It does not have a lot of options."   

What Japan could immediately do is to contribute financially to the campaign as it did during the 1991 Gulf War, or expand its commitment to humanitarian help in the Middle East. It was in fact that commitment that led to the crisis that ended Saturday with Goto's death.   

During a tour of the region in January, Abe pledged $200 million in nonmilitary assistance to support countries affected by the campaign against ISIS. That's the exact same amount ISIS demanded in ransom, an amount so high, many speculated it never expected payment and knew all along it would kill its captives.

Now, that is exactly what has happened. "To the terrorists, we will never forgive them for this act," Abe said. And if he pushes through a constitutional change, his words may soon be accompanied by action. 

An earlier version of this story stated that the government may choose to amend article 98 of the constitution. In fact, the government may choose to amend article 96.