US Vice President Joe Biden and his wife Jill signed a condolence book at the Turkish embassy in Washington for victims of the Istanbul airport attack.
Islamic State militants were suspected to have carried out Tuesday's attacks , which killed 42 people and wounded 239 at Europe's third-busiest airport.
He said the attacks on the airport had the effect of unifying the world against "distorted jihadists" but that defeating them would take some time.
I am absolutely convinced that combined with our resolve, we will wipe out the so called caliphate in Iraq and in Syria.
The world is united behind Turkey in our resolve.
Suicide bombers targetting Istanbul's airport incited panic to take lethal advantage in an attack that echoed the Brussels airport atrocity.
The gun and bomb attack at Istanbul's Ataturk Airport is the latest in a series of deadly incidents in Turkey this year.
Istanbul's busiest airport has been targeted in a deadly gun and bomb attack - here's what we know so far.