"I've only seen that in the open press," Croft said on Tuesday. "It's a very expensive complicated system, but I've seen no evidence that that is actually going to happen."
Croft also said the Iraqi authorities have not consulted with the United States about the purchase of the Russian air defense system.
In February, Iraqi Foreign Minister Ibrahim Jaafari told Sputnik that Iraq was negotiating the purchase of S-400 air defense missile systems from Russia, but possible US sanctions could be an obstacle to that. US State Department spokeswoman Heather Nauert said that the United States had informed governments around the world, including the Iraqi government, of possible consequences under the US Countering America's Adversaries Through Sanctions Act (CAATSA).
The S-400 Triumph is Russia's newest long-range anti-aircraft missile system. It is designed to destroy aircraft as well as cruise and ballistic missiles, including medium-range missiles, while it can also be used against ground targets. The range of the S-400 is 400 kilometers and it is capable of destroying targets at an altitude of up to 30 kilometers.