Washington: The Obama administration’s top aviation security official says hardened militants in Syria known as the Khorasan group represent “a clear and present danger” to passenger and cargo airline flights to the United States and Europe.

The head of the Transportation Security Administration, John Pistole, says the purpose of US military air strikes last week that targeted the group was to disrupt an “imminent attack or attack entering the last phases of execution”.

Pistole says the Khorasan group has been researching and testing improvised explosive devices designed to elude airport security. He also says the group was recruiting Westerners to carry a bomb onto a passenger plane or put one on a cargo plane. He says these Westerners may not be on the US government’s terror watch list.