Sen. John McCain (R-Ariz.) described the Islamic State as a "direct threat to the United States of America." (Joshua Roberts/Reuters)

Sen. John McCain said Sunday that President Obama is "either in denial or overwhelmed" with regard to the Islamic State and called for “additional U.S. troops” to help combat the extremist group.

The Arizona Republican, speaking on CBS's "Face the Nation," added that U.S. forces should play only a support role.

McCain described the Islamic State as a "direct threat to the United States of America,” adding that it "may be one of the biggest we’ve ever faced.”

He called on the administration to send weapons to Iraq's Kurdish fighters and conduct airstrikes in Iraq and Syria to beat back the threat posed by the Islamic State.

Sen. John McCain (R-Ariz.), speaking on CBS's "Face the Nation," called for additional U.S. troops to help combat the Islamic State. (Reuters)