Suicide bombers struck Friday prayers at two different mosques in the Yemeni capital of Sanaa, in attacks that killed more than 130 people and injured hundreds of others. Representatives of the Islamic State claimed responsibility for the attack—the second time this week the group has taken credit for an attack far from its main base in Iraq and Syria, after gunmen stormed the Bardo Museum in Tunisia on Wednesday—though the claims could not be verified in either case.

Was It ISIS?

"A statement from the group [claiming responsibility] was published on Twitter accounts known as reliable sources for IS propaganda," the BBC reported. "If confirmed, the attacks would be the first carried out by IS in Yemen."

The United States cast doubt on that claim, however. The White House, in the New York Times' words, reported "no indications of an operational link between the Islamic State group and Friday's attacks."

In a statement of condemnation, the State Department did not specifically identify the Islamic State as being responsible for the Sanaa bombings, instead deploring "the brutality of the terrorists who perpetrated today’s unprovoked attack on Yemeni citizens who were peacefully engaging in Friday prayers in their places of worship."

Al-Qaeda's powerful branch in Yemen, The New York Times noted, released a statement calling Friday's bombings "unlawful."

The Possibility of Civil War

"The death toll was expected to rise," The Wall Street Journal reported, quoting Yemeni security officials, adding that "it was already the highest ever in Yemen for a single terrorist operation."

The attacks reinforced fears that the country's ongoing a sectarian power struggle could turn into a full-blown civil war. Since Houthi rebels backed by Iran took control of the capital earlier this year, the country has also been largely leaderless. As Yemen expert Gregory Johnsen noted on Twitter, "Yemen has no president, no vice president, no prime minister and no cabinet. It does have 2 former presidents and lots of guns."

In recent days, clashes have erupted over control of an airport in the southern city of Aden; a notable pro-Houthi journalist was assassinated; and an airstrike targeted the presidential palace in Aden.

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