WASHINGTON -- U.S. intelligence agencies have no direct evidence that a terrorist group caused a Russian passenger jet to break up over the Sinai Peninsula but haven't dismissed the possibility, the top U.S. intelligence official said Monday.
"It's unlikely but I wouldn't rule it out," Director of National Intelligence James R. Clapper said about the possibility that a terrorist group brought down the plane, killing all 217 passengers and seven crew members.
"We don't have any direct evidence of any terrorist involvement yet. ISIL had tweeted claims," Clapper said, using an alternative acronym for the Islamic State group. Clapper spoke at a conference hosted by the military news website Defense One.
Wilayat Sinai, Islamic State's affiliate in Egypt, claimed responsibility on Twitter for downing the Airbus A321 on Saturday as it flew from the coastal resort of Sharm el-Sheikh to St. Petersburg. The group's message cited Russia's air war in Syria.
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The group posted a grainy video that appears to show a jetliner exploding in the sky and falling with a trail of smoke behind it. The video doesn't show any geographic landmarks or evidence suggesting where or when the explosion occurred.
U.S. officials have said they believe that the jetliner was flying too high to have been hit by a surface-to-air missile.
Wilayat Sinai is one of the most effective groups attacking the Egyptian military in the Sinai Peninsula, said a U.S. official, who spoke on the condition of anonymity to discuss internal assessments.
The group, formerly known as Ansar Bayt al Maqdis, or Partisans of Jerusalem, recently swore a loyalty oath to Islamic State and its leader Abu Bakr Baghdadi.
The aircraft was flown by a Russian charter airline company called Metrojet. Company officials told reporters in Moscow on Monday that the crash did not result from pilot error or technical problems with the aircraft.