Thursday's White House decision to authorize airstrikes in Iraq was met with support from key defense lawmakers on Capitol Hill, who called it an unsettling but necessary step forward.

Congress has been wary of any new prolonged intervention in Iraq, but has also pushed President Obama to ensure security gains made by American troops during the eight-year Iraq War aren't erased by advancing Islamic State fighters.

In a statement late Thursday night, Sens. John McCain, R-Ariz., and Lindsey Graham, R-S.C., called the humanitarian drops and military strikes the "right" thing for U.S. forces to do, but added they still believe airstrikes will not be enough to deal with the insurgent threat.

"We need a strategic approach, not just a humanitarian one," they said. "A policy of containment will not work against [Islamic State]. It is inherently expansionist and must be stopped. The longer we wait to act, the worse this threat will become, as recent events clearly show."

They and other Republicans have pushed for additional military support to Iraqi and Syrian forces, regardless of whether the current Iraqi government is restructured.

But Rep. Adam Smith, D-Wash., ranking Democrat on the House Armed Services Committee, firmly opposed that idea.

"We must continue to remember that the U.S. militarily alone cannot resolve this conflict," he said in a statement. "In order for real and lasting peace to take hold, the Iraqi people must create an inclusive and fully representative government. It is long past time that the Iraqi government step-up and confront [Islamic State], both militarily and politically."

White House officials said they are working to keep Congress informed of all U.S. military actions in Iraq, and expect to be in contact with key leaders throughout the weekend.