Japanese citizens awoke Sunday to a harrowing video purporting to show the beheading of Japanese journalist Kenji Goto at the hands of terror group Islamic State (also known as ISIS or ISIL). While members of the group vowed that the ”nightmare for Japan” had just begun, Japanese prime minister Shinzo Abe vowed to make the killers “pay for their sins.”

“Japan will not give in to terrorism,” Abe said.

Goto, a war correspondent with a wife and three children, devoted much of his work to reporting on the families and children affected by conflict. His mother Junko Ishido, 78, said in a press conference following the news of his death: “It is my only hope that we can carry on with Kenji’s mission to save the children from war and poverty.” She added, “Kenji has left us on a journey.”

Japan may also face a new journey. For years, the country’s role on the international stage has been limited to providing humanitarian aid. Now the country faces two choices: pulling back into a new kind of isolationism or casting off its pacifist principles, a direction the Abe camp has been campaigning for. Critics of the prime minister say his new assertiveness in foreign policy is what put Goto and Haruna Yukawa, another hostage killed a week earlier, at risk in the first place.

Japan has not been directly involved in efforts to fight the Islamist terror group, but last month Abe announced $200 million in humanitarian aid for countries battling ISIL, the amount in ransom that the hostage-takers demanded before killing their captives. After the video of Goto’s murder was released, Abe said he would in fact expand its aid to the region. The government also said it would strengthen security for Japanese operations around the world and boost intelligence operations. ”This is 9/11 for Japan,” Kunihiko Miyake, a Japanese diplomat, told The New York Times.

But years of taking a backseat in international affairs means Japan may be unprepared for the kind of role that Abe envisions. Japan’s government lacked contacts in the Middle East and depended on Jordan, which was trying to negotiate the release of a pilot, for negotiating with the extremist group, analysts pointed out. Critics said it would have been wiser to rely more on Turkey, which has managed the release of captives in the past.

Last year, Japan revised an interpretation of its constitution to allow its military to assist allies in war or intervene to protect Japanese citizens overseas. Parliament is expected to discuss legislation related to that interpretation this month—the killings of Goto and Yukawa will loom large over the debate.