WASHINGTON - U.S. President Donald Trump has approved sending American troops to bolster Saudi Arabia's air defenses after Saturday's attacks on the kingdom's oil facilities, which Washington has blamed on Iran, the Pentagon said on Friday.

The Pentagon said the deployment would involve a moderate number of troops and would be primarily defensive in nature. U.S. Marine General Joseph Dunford, chairman of the Joint Chiefs of Staff, said the deployment would not reach thousands of forces but he declined to be more specific.

(Reporting by Phil Stewart and Idrees Ali Editing by Chizu Nomiyama ) ((phillip.stewart@thomsonreuters.com; 1-202-898-8398; Reuters Messaging: phillip.stewart.thomsonreuters.com@reuters.net))