A video released on Islamic State-affiliated Twitter accounts shows the apparent beheading of Haruna Yukawa, a 42-year-old Japanese citizen who had been held captive by ISIS forces since last August. Yukawa's death hasn't been independently verified, but the Japanese government said it believes the video to be authentic. The beheading came days after ISIS demanded Japan pay a $200 million ransom to free Yukawa and Kenji Goto, a 47-year-old journalist and fellow captive. The Japanese government had pledged to free the hostages, but said it would not "bow to terrorism." According to Goto, who spoke in the video that showed Yukawa's purported execution, ISIS will free him if Sajida Mubarak al-Rishawi, a female affiliate currently imprisoned in Jordan, is released.

In a hastily arranged news conference, Japan reacted with outrage.

"The Japanese government will not give in to terrorism and will continue to contribute to the peace and stability of the international community and the world," Prime Minister Shinzo Abe told reporters.

For Abe, whose Liberal Democratic Party did well in regional elections in December, the crisis with the Islamic State presents Japan with a dilemma. Since assuming the country's top office, Abe has supported removing Article 9 of Japan's constitution, a pacifist measure that has guided Japanese foreign policy since World War II. The prime minister has argued that the clause has become anachronistic in a world where China, a longtime adversary, has greatly improved its military capacity. Following the elections in December, Defense Minister Gen Nakatami explained the rationale.