WASHINGTON (AFP) - President Donald Trump said Friday (Nov 3) that the Islamic State in Iraq and Syria (ISIS) will pay a "big price" for every attack it stages against the United States, following the New York truck attack by an ISIS loyalist.

The US military has hit ISIS "much harder" over the past two days after the militant group claimed the attacker was one of their soldiers, Trump said.

"They will pay a big price for every attack on us!" Trump wrote on Twitter. The New York attack Tuesday left eight dead and 12 wounded.

Trump has said the alleged attacker, Uzbek immigrant Sayfullo Saipov, 29, should be executed.

Trump backed off initial comments that he would like to see the man sent to the US prison for terror suspects at Guantanamo Bay, Cuba.