Washington: US Director of National Intelligence James Clapper said Monday he knew of no direct evidence that terrorism was to blame for the weekend crash of a Russian passenger plane in Egypt.
Speaking at a Washington defense conference, Clapper said it was "unlikely" that the Islamic State group had the capacity to carry out such an attack, but added: "I wouldn't rule it out."
"We don't have any direct evidence of any terrorist involvement yet," he said.
Both Cairo and Moscow have played down a claim from the Islamic State group's Egypt branch that it brought down the aircraft linking holiday destination Sharm el-Sheikh and Russia on Saturday, killing all 224 on board.
"ISIL has claimed responsibility," Clapper said, using an alternate acronym for IS, "but we really don't know" if it is involved.
Once black box information has been analyzed "perhaps we will know more," he added.
Other US officials also said it was too early to link the crash to Islamic State terrorism.
Nicholas Rasmussen, director of the National Counterterrorism Center, told the defense conference that the investigation is still ongoing, but "at this point, we've got nothing in intelligence to corroborate a nexus to terrorism."