An Oscar-worthy foreign policy question is arising as the 2024 presidential race heats up: Can America be everything, everywhere, all at once?

One potential GOP candidate, Governor DeSantis of Florida, apparently doesn’t think so. “While the U.S. has many vital national interests — securing our borders, addressing the crisis of readiness within our military, achieving energy security and independence, and checking the economic, cultural, and military power of the Chinese Communist Party — becoming further entangled in a territorial dispute between Ukraine and Russia is not one of them,” he said this week.

The Florida governor was reacting to a survey of declared and presumed Republican presidential candidates, which was initiated by the anti-interventionist Fox News commentator Tucker Carlson, about America’s Ukraine policy.

Republicans are increasingly distancing themselves from President Reagan’s muscular approach to world affairs, lining up instead behind President Trump’s suspicion of all foreign engagements. Asked about Mr. DeSantis’s answer to the Fox survey, Mr. Trump muttered, “Whatever I want he wants now.”

Some Republicans remain loyal to the party’s legacy of projecting American power around the globe. “When the United States supports Ukraine in their fight against Putin, we follow the Reagan doctrine,” Vice President Pence told Mr. Carlson. “If Putin isn’t stopped and the sovereign nation of Ukraine is not restored quickly, he will continue to move toward our NATO allies.” Then, he added, America would be forced to send GIs to Europe. 

Another Republican agreed, urging the president to “provide arms to Ukraine. They want to fight their good fight. They’re not asking us to fight it for them. And the president has steadfastly refused. And I think that that’s a mistake.”

Except that was Mr. DeStantis when he was a congressman, in a 2016 interview with a Reagan alum, Bill Bennett. At that time, Mr. DeSantis was railing against President Obama’s foreign policy weakness. The governor’s current position is more than a mere flip-flop: It represents a deep unease among Republicans — as well as many Democrats — who feel that America is spread too thin around the globe. 

America has a tendency to tire of long-protracted military commitments. Since Vietnam we gave up in Iraq, Afghanistan, Libya, and elsewhere. President Putin has concluded that if the Ukrainian war drags on long enough, Washington would turn its back on Kyiv as well. 

“Vladimir Putin seems to believe that time is not on the Ukrainians’ side,” a former secretary of state, Condoleezza Rice, said recently. “I don’t think that’s right, but we have to do everything that we can to convince him that it is indeed wrong.”

To do so, some of Mr. Biden’s hawkish critics say, America must go all in. The current pace of arming Ukraine is too slow. As Mr. DeSantis pointed out at the time, it was the Obama-Biden administration that refused to sell Kyiv arms after Russia invaded and annexed Crimea in 2014, which may have encouraged Mr. Putin’s invasion last year. 

Since then, Mr. Biden hemmed and hawed about sending anything from artillery to tanks, declining deliveries of arms Kyiv begged to get, before eventually supplying them. Currently, the Pentagon is undecided about sending F-16 fighter jets to Ukraine, even as Kyiv insists it needs them for winning a looming spring battle. 

Some of the president’s critics point out that too much attention is being paid to Ukraine altogether. As Mr. DeSantis argued, the “power of the Chinese Communist Party” is of much higher priority for America.

Yet, as Beijing is fast building global alliances, tightening relations with Russia, Iran, North Korea — and as a neo-“NonAllied” bloc sides with it in Latin America, Africa, Asia, and the Mideast — can America afford to leave any of our allies behind?

The idea that America must neglect one part of the globe in order to strengthen our position in another informed the “pivot to Asia” conceit: Obamaites said they would reduce naval presence in the Atlantic to strengthen it in the Pacific. In reality, presence in both oceans was reduced, but more so in the Atlantic. 

Now, America is striving to catch up on decades of lowered military commitments — both in Europe and in Asia. In the Mideast, a region several presidents attempted to leave behind altogether, Communist China is making huge strides. Beyond the Islamic Republic, Beijing is now cozying up to Saudi Arabia. 

Yet, didn’t we care about the Mideast  only because of oil? As we slowly wean ourselves from reliance on fossil fuel, many argue, the region is bound to lose its prominence.

Earlier this month, though, Tehran announced a discovery of the world’s second largest reserve of lithium. An essential component of batteries used in, among others, electric vehicles, Communist China has cornered the lithium processing market. 

During World War II President Roosevelt decided, against the advice of General MacArthur, to first win in Europe even though the Japanese attack at Pearl Harbor was the reason for entering the war. Yet, America fought, and ended up winning, in both theaters.

The question now is not whether we can afford fighting in this or that part of the world, but whether we can afford not to.