Officials told lawmakers on Tuesday that a small group of violent terrorists will attempt to overcome the logistical challenges of mounting such an attack.

In a testimony before congressional committees, Director of National Intelligence James Clapper and other officials described ISIS as the 'pre-eminent terrorist threat.'

The militant group can 'direct and inspire attacks against a wide range of targets around the world', Clapper said.

Marine Lt. Gen. Vincent Stewart, director of the Defense Intelligence Agency, said ISIS will probably conduct additional attacks in Europe and then attempt the same in the US.

He said US intelligence agencies believe ISIS leaders will be 'increasingly involved in directing attacks rather than just encouraging lone attackers.'

Clapper also said al-Qaida, from which ISIS spun off, remains an enemy, Daily Mail reported.

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