As President Biden seeks additional security assistance for Ukraine, concerns are growing in Washington that America lacks sufficient stockpiles to support three separate conflicts across Europe, the Middle East, and Asia.

That, at least, is what Senator Vance is warning his Senate colleagues in an attempt to draw support for a new flavor of foreign policy on Capitol Hill — hawkish realism. In a memo released Thursday, Mr. Vance argued that “blank check” support for Ukraine is undermining America’s capacity to aid Israel in its war with Hamas and to defend Taiwan in the event of a Chinese attack.

“A three-front scenario has become plausible because the Biden administration has failed to articulate a clear strategy to bring active hostilities to a close in Ukraine,” Mr. Vance asserted. This “strategic failure,” he says, “was premised, not on any strategic appreciation of the finite U.S. capacity to enable Ukraine’s legitimate aspirations, but upon the unrealistic hope that no other, significant demands would be made upon U.S. resources.”

While America retains a secure stockpile of advanced munition systems that can help Israel fight Hamas, other critical stockpiles are at risk of depletion. At greatest risk are the air defense missiles that both Ukraine and Israel employ to destroy inbound threats from their respective aggressors. 

The Israeli air defense system, the Iron Dome, relies on the American production of crucial components for Israel to effectively intercept rockets launched by Hamas, the memo states. Competing foreign policy priorities in Ukraine and Taiwan, which also rely on this supply chain of solid rocket motors, appear to be cutting into America’s ability to supply systems of anti-aircraft missiles. 

Another American missile defense system being strained is the Patriot battery, one of the most advanced air defense systems in the Yankee arsenal. President Zelensky has argued to Washington that to fend off Russian attacks, Ukraine depends heavily on Patriot interceptors. Each month of the war with Russia, Mr. Vance writes, Ukraine consumes 160 or more of these interceptors, eating into the likely supply of 2,000 produced in America since 2017.

American military pledges to Taiwan are now at risk, to hear these realist hawks tell it. “Israel is unlikely to require Patriots at this stage in its conflict in Gaza, but Patriot components are reportedly among supplies promised to Taiwan on backorder since 2019,” Mr. Vance writes, citing open-source data because the numbers on critical American weapons systems are classified. 

Man-portable missile systems, which are used against low-flying aircraft, are also on backorder to Taiwan for four to eight years, Mr. Vance warns. This “critically short supply,” widely used in Ukraine, “have almost certainly had a negative impact on Taiwanese defense planning, force modernization, and readiness,” he writes, “further eroding our capacity to deter the PRC from attempting to conquer Taiwan.”

Also at stake are 155mm artillery shells, a critical round first developed by the French in response to the trench warfare of World War I. Ukraine is using 300,000 of the U.S.’s war reserve stock of these shells, situated in Israel. That number, Mr. Vance calculates, is nearly 10 times what Israel used in Gaza in 2014.

U.S. officials purported to repurpose tens of thousands of shells meant for Ukraine back to Israel last month. Yet even as America ramps up its shell production over the next two years, Mr. Vance foresees that “155mm supplies globally in 2024 will almost certainly be constrained.”

While the Republican Party grows increasingly isolationist, Mr. Vance joins other Senate Republicans in voicing opposition to such populist sentiment as war in Ukraine drags on and the potential for a Taiwan invasion looms large. These so-called defense hawks favor bolstering the U.S. military arsenal, but directing its energy toward winnable conflicts. “Israel has an achievable objective,” Mr. Vance wrote in a memo last month. “Ukraine does not.”

A growing number of foreign policy realists share Mr. Vance’s concerns. They fear that diverting military and financial stockpiles to Ukraine will degrade America’s ability to defend itself should it enter a war with China, as the Sun has reported. The Biden administration has committed more than $44.5 billion in security assistance to Ukraine since Russia’s invasion in February 2022. 

The Pentagon’s list of military equipment given to Ukraine thus far includes a grant of 2.8 million artillery shells, a number that instills trepidation in a retired American officer, Lieutenant Colonel Daniel Davis. These shells are “designed so that we can sustain long-term combat operations if necessary,” he tells the Sun. “If we stopped giving shells today and never gave another one to Ukraine, it would take four or five years to just recover our own inventory.”

Although proponents of heightened aid to Ukraine often argue that the military supplies come from the American military’s excess inventory, Mr. Davis says that this inventory is designed to provide immediate replacements on the frontlines in case the nation must prepare for its own combat. “It takes years to build new tanks — Abrams or Bradley’s or any of these other kinds of high-end weapons systems — years,” he says.

Those who see America’s military support for Ukraine as within the national interest are especially worried about “the decline of America’s defenses — military and political.” That’s how the editor of the editorial page of the Wall Street Journal, Paul Gigot, put it during his speech at the American Enterprise Institute, where he was honored on Tuesday. 

“We are facing an array of adversaries that is more formidable than at any time since World War II,” Mr. Gigot said, “and we aren’t prepared for the moment.” He cited the insufficient production of the Navy’s attack submarines, which are “the best deterrent we have against a Chinese invasion of Taiwan.” Meanwhile, U.S. defense spending is now at its lowest point as a share of the economy since World War II. 

President Reagan’s combination of realism and idealism, or what an American political economist, Charles Krauthammer, called “democratic realism,” is how Mr. Gigot describes his foreign policy views, he tells the Sun. To protect Israel and Ukraine, he said on Tuesday, is to protect Western civilization. “In helping them defend themselves,” he asserted, “we are also defending our values.”