MACDILL AIR FORCE BASE, Fla. (Reuters) - President Barack Obama vowed on Wednesday that the United States will not fight another ground war in Iraq, seeking to reassure Americans about the level of U.S. involvement after a top general suggested some combat troops could be deployed.

Obama, who has spent much of his presidency distancing himself from the Iraq war, stressed during a speech at MacDill Air Force Base in Tampa that airstrikes would be the central U.S. contribution to the fight against Islamic State in Iraq and Syria (ISIS), along with coordinating a coalition that he said now includes more than 40 countries.

"I want to be clear," he said. "The American forces that have been deployed to Iraq do not and will not have a combat mission."

His message came a day after General Martin Dempsey, chairman of the U.S. Joint Chiefs of Staff, left the door slightly ajar to the possibility of some ground forces during congressional testimony that worried some Democrats.

"As your commander in chief I will not commit you and the rest of our armed forces to fighting another ground war in Iraq," Obama said.