They called them isolationists. In 1941, “America First” was a powerful political movement in the United States, firmly opposed to U.S. entry into World War II.

Its leadership included American heroes like Charles Lindbergh. Its grassroots organizers included young up-and-comers like Yale Law School students Robert Douglas Stuart Jr. and Gerald Ford.

The America First Committee represented a diverse group of political opinions, too. They balked at being labeled “isolationists.” In fact, the committee lobbied heavily to rebuild the U.S. military.

Many of their pronouncements could have come out of President Reagan’s “peace through strength” playbook.

America First also had no qualms about using force. Shortly, after Pearl Harbor, the committee disbanded.

Lindbergh volunteered his services to the War Department. Stuart joined the Army, rising to the rank of major. Gerald Ford fought in the Navy.

Not that much has changed in America since their day. There is, and always likely will be, a strain of isolationism in American foreign policy, just as there will always be some who believe the right response to any country that crosses U.S. interests is to invade.

Neither position offers a practical course for all situations. Nor does it make much sense to caricature American foreign policy in these terms.

Many progressives are dismayed by President Obama’s call for military intervention in Syria. Code Pink, for example, had gushed over candidate Obama because they thought he shared their simplistic view of “no war, no more.” Now they feel betrayed.

But, despite his self-proclaimed preference for “leading from behind” in international conflict, Mr. Obama is no isolationist. He believes in international interventions as much — maybe more — than his predecessor George W. Bush.

And that is not at all unusual among those on the left, even among progressives. The left is not monolithically anti-war any more than the right is reflexively pro-war.

Left and right do, however, differ fundamentally over the purposes of war. Conservatives believe the primary measure of when to use force is when it serves critical national interests. Liberals believe it is most appropriate to use force in the service of others.

Still, when it comes to applying their principles to a specific go/no-go decision on the use of military force, the left is just as much all over the place as is the right.

There is lesson to be learned here. It is a mistake to look at debates within both the conservative and the progressive movements as a pitched battle between innate isolationists and congenital interventionists.

Foreign policy is far too complicated to break along such simplistic fault lines. And it is dumb politics to think any leader in either movement could build a majority by flying the banner of isolationism or interventionism.

Even when such views seem to poll well, the polls are little more than the “flavor of the month.” They only superficially reflect how Americans feel about how our interests are best looked after overseas.

What most Americans really want is leader who will address foreign policy challenges with prudence and judgment. And what conservatives demand is that the decision-makers put the interests of Americans first, above any political calculations.

In the current debate over Syria, conservative leaders have an opportunity to lead. If they want to make an enduring impression rather garner a flash of popularity, if they want to be seen as leaders of character who deserve to be entrusted with the safety of the nation — then they need to demonstrate their judgment, not just express an opinion.

They need articulate a strong, rationale and focused foreign policy that refuses to run toward either isolationist or interventionist extreme.

- James Jay Carafano, a Washington Examiner columnist, is vice president for defense and foreign policy studies at the Heritage Foundation.