On Monday, Republican presidential candidate Mitt Romney delivered a foreign policy speech to cadets at the Virginia Military Institute in Lexington, Va. He was correct in his indictment of the Obama administration for its numerous failures -- especially in the Middle East -- and his embrace of Ronald Reagan's "peace through strength" philosophy. A strong and respected America is less likely to be attacked.

The Obama administration's approach to foreign policy has been one of apology, genuflection toward dictators and inconsistency. "[I]t is the responsibility of our president to use America's great power to shape history," Romney told the VMI cadets. "Not to lead from behind, leaving our destiny at the mercy of events. Unfortunately, that's exactly where we find ourselves in the Middle East under President Obama."

Romney reached back more than 60 years for this quote from George Marshall, secretary of defense in the Truman administration: "The only way human beings can win a war is to prevent it." The Korean and Vietnam Wars followed. Were they preventable?

Romney's speech was serious, especially this line which came after his call for a "change in course in the Middle East": "That course should be organized around these bedrock principles: America must have confidence in our cause, clarity in our purpose and resolve in our might."

I'm fine with that, but perhaps in the Oct. 22 presidential debate on foreign policy, moderator Bob Schieffer might ask Romney what is our cause, what is our purpose and where has might, alone, caused that purpose to be successful? Iraq? Afghanistan? Vietnam? Will it work with Iran? Does Romney think bombing Iran, with or without Israel's assistance, will deter the mullahs from their goal of acquiring nuclear weapons? Maybe it would, but can he be sure?

Would Israel, and possibly America, be able to tolerate a counterstrike and possible terrorist acts on U.S. soil by Iranian and Hezbollah agents who could very well be in the U.S. already, awaiting instructions?

John F. Kennedy said in his 1961 inaugural address that we were willing to "... pay any price, bear any burden, meet any hardship, support any friend, oppose any foe, in order to assure the survival and success of liberty." Eleven years later, as America was being torn apart by the Vietnam War, Democratic presidential candidate George McGovern said the United States "... can't be the policeman of the world."

Who is right? I think both are. America's role in the world must be redefined and re-explained. The presidential candidates should be asked about it. We can't afford to go everywhere and do everything, and it isn't fair to our young men and women who are asked to die or lose limbs. It isn't fair to taxpayers who must fund these wars. Yet America still has an interest in promoting liberty and freeing people from tyranny -- an interest both moral and self-serving, because democracies don't attack each other. But when and how should we act?

The flaw in Romney's speech was his restatement of the policy of the current and previous administration, that a Palestinian state adjacent to Israel is the key to Middle East peace. There is no evidence that the Palestinian-Arab-Muslim world shares this goal. Radical Islamists teach, preach and act as if their objective is the elimination of Israel. The Palestinian leadership has not lived up to a single promise or agreement, even when Israel has sacrificed land and lives in the pursuit of a Western mirage.

Western values -- including religious values -- can't be forced on people who don't share them. There is a fundamental gap between Islamic cultures and the West that cannot be easily bridged through diplomacy or military might.

Romney's VMI speech sounded good to some American ears, but what does it mean to the rest of the world, which faces not invading armies but invading terrorists without uniforms or a nation-state? Perhaps Bob Schieffer will ask Romney and President Obama to answer these questions.

Examiner Columnist Cal Thomas is nationally syndicated by Tribune Media.