There is no indication that the rifle will be adopted by the United States Armed Forces other than in the Marine Corps as the IAR or M27, but the elite Delta Force and other United States special operations units have fielded the HK416 in combat, and Oklahoma Senator Tom Coburn has called for "free and open competition" to determine whether the army should buy the HK416 or continue to purchase more M4 carbines. Incoming United States Secretary of the Army Pete Geren agreed in July 2007 to hold a "dust chamber" test pitting the M4 against the Heckler & Koch HK416 and XM8, as well as the rival FN SCAR design. Coburn had threatened to stop Geren's Senate confirmation if he did not agree to the test. The Heckler & Koch XM8 and FN SCAR had the fewest failures in the test, closely followed by the HK416, while the M4 had by far the most. In 2007, the Norwegian Army became the first to field the HK416 as a standard-issue rifle.