WASHINGTON (AFP) - Director of US National Intelligence James Clapper said on Monday (Nov 2) that 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 defence conference, he said it was "unlikely" that the Islamic State in Iraq and Syria (ISIS) militant 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 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," Mr Clapper said, using an alternate acronym for ISIS, "but we really don't know" if it is involved.
Once black box information has been analysed "perhaps we will know more", he added.
Other US officials also said it was too early to link the crash to ISIS terrorism.
Mr Nicholas Rasmussen, director of the National Counterterrorism Centre, told the defence conference that the investigation is still ongoing, but "at this point, we've got nothing in intelligence to corroborate a nexus to terrorism".
State Department spokesman Elizabeth Trudeau said of the idea that the plane was downed by the ISIS: "We've seen no reports that would support that."
A US defence official also said he was sceptical. This official said missiles able to shoot down a plane at high altitude are owned by "state actors".
The Russian airline has said the Airbus 321 came down due to "external" factors and that "no technical failures" could account for its apparent break-up in mid-air.
Investigators are examining all possible causes as they comb the remote crash site in the Sinai peninsula as part of an Egyptian-led probe into the disaster that also involves experts from Russia, Airbus and Ireland, where the aircraft was registered.