Explosion outside Kabul airport, casualties unclear: Pentagon

The US military confirmed Thursday that a large explosion occurred outside the Kabul airport in Afghanistan, as the US-led airlift of thousands continued inside the compound.

"We can confirm an explosion outside Kabul airport. Casualties are unclear at this time. We will provide additional details when we can," said Pentagon Spokesman John Kirby.

US and allied officials have said they had intelligence that suicide bombers were threatening to attack the airport.