Texas Gov. Rick Perry and Kentucky Sen. Rand Paul aren't waiting for the 2016 Republican presidential primary race to debate each other about American foreign policy. But though the political fallout of their dispute is drawing ample attention, the consequences of the United States' future role in the world aren't limited to who wins the GOP nomination.

After protracted military missions in Afghanistan and Iraq, most Americans are understandably war weary. And many fairly find fault with not just President George W. Bush's decision to invade Iraq in 2003 but the way his administration handled that operation - and the one that began in Afghanistan in 2001.

Yet many Americans also are rightly wary about President Barack Obama's confusion and missteps on the world stage. His failure to back up his "red line" ultimatum in Syria dangerously underscored his general approach of U.S. retreat.

And no, White House spokesman Josh Earnest didn't sound convincing Monday with his curious contention that the president "has substantially furthered American interests and substantially improved the, uh, you know, the - the tranquility of the global community."

Still, while partisan blame games dominate the perpetual modern campaign, crafting a positive U.S. foreign policy going forward won't be as easy as pointing fingers at presidential mistakes of the past - or present.

Yes, our nation must strive to avoid extended armed interventions that inflict terrible tolls in blood and treasure only to produce disappointing results - as in Iraq.

We also must recognize, though, that if America keeps backing away from its long-time role as the strongest global - and military - force for good, the vacuum left by our withdrawal will not go unfilled.

Over the last few years, China's armed buildup and aggressive tone have sent ominous signals in East Asia.

However, the continuing Islamic radical terror threat remains the most pressing menace to the U.S. and its allies.

Gov. Perry correctly stressed that point in a guest column in last Friday's Washington Post. He challenged Sen. Paul's assertion, made in a recent Wall Street Journal guest column of his own, that President Ronald Reagan would have stayed out of Iraq's ongoing civil war.

Gov. Perry wrote: "In today's world, with today's threats, we still cannot 'take blind shelter across the sea, rushing to respond only after freedom is lost.' That was President Reagan's warning. Sen. Paul would be wise to heed it."

But Gov. Perry - and the rest of us - would also be wise to ponder these vexing questions from Sen. Paul in that column:

"What would airstrikes accomplish? We know that Iran is aiding the Iraqi government against ISIS. Do we want to, in effect, become Iran's air force? What's in this for Iran? Why should we choose a side, and if we do, who are we really helping?"

Such high-stakes puzzles aren't limited to what America should, or shouldn't, do about the current crisis in Iraq.

These dilemmas also apply to other distant realms when unchecked chaos endangers not just U.S. interests there but ultimately the security of our American homeland.

Thus, 2016 presidential candidates, regardless of party, must do more than find fault with foreign policies of the past and even the present.

They must present a coherent vision for an effective foreign policy of the future.

And it's not too soon for that crucial debate to begin.