Salary cost alone is in the neighborhood of 2.5 mil per day. That's before we add up all the operational costs to the military of being there.
I suspect when the US says 350 million donation that it's talking about a different pot of money than that from which pay and costs come from.
How much does it cost to steam an aircraft carrier across the ocean? Fly a cargo plane? Set up a military hospital?
They were over there anyway so these costs would have been incurred by the Pentagon regardless.