Defense Secretary Ash Carter is defending the U.S. strategy for defeating the Islamic State group.

He tells the Senate Armed Services Committee that U.S.-backed local forces in Iraq and Syria are making substantive gains toward retaking Islamic State strongholds.

Carter is also advising against an American-led "foreign ground force" to battle the Islamic State. He says that would play into the hands of the extremists.

Carter says U.S. cyberattacks against the Islamic State are continuing and aim to disrupt the group's financial support and recruiting abilities.

Gen. Joseph Dunford is chairman of the Joint Chiefs of Staff. Dunford says the U.S. wants to drive the extremists into "virtual isolation."

But Senator John McCain of Arizona says military operations are being micromanaged in Washington. McCain is committee chairman.