WASHINGTON (CNN) -- Defense Secretary Robert Gates on Tuesday said the troop increase plan in Iraq that the Bush administration calls a "surge" is "not the last chance" in Iraq.

Many people agree that there would be "serious consequences for this country and for the region were we to leave Iraq in chaos," said Gates, testifying before the Senate Armed Services Committee. He was responding to questions and remarks from Sen. John Warner, R-Va., who cited quotes from people calling the surge operation "the last chance," or, "the last, best chance."

"To me, that type of rhetoric is inviting -- almost it's a timetable for the Baghdad operation. If it doesn't succeed, it was our last chance," Warner said. The surge involves an increase of 21,500 U.S. troops in Iraq, with most in Baghdad and some in Anbar province.

Warner asked whether the administration is "thinking beyond the Baghdad operation" to develop other ways to help the Iraqi government in case the plan doesn't meet its goals.

Gates said he is thinking about "alternatives."

"I think that if this operation were not to succeed -- and we clearly are hoping it will succeed, planning for it to succeed, allocating the resources for it to succeed -- but I would tell you that I think I would be irresponsible if I weren't thinking about what the alternatives might be if that didn't happen. But we, at this point, are planning for its success," he said.