President Biden, in his prime-time address to the nation this month, called America the “arsenal of democracy,” evoking President Franklin D. Roosevelt’s message to a nation emerging from the Great Depression that it had the industrial base and know-how to arm Britain and other countries fighting Nazi Germany.

“Just as in World War II, today, patriotic American workers are building the arsenal of democracy and serving the cause of freedom,” Mr. Biden said Oct. 19 in remarks from the Oval Office.

Like the days before the U.S. entered World War II, countries asking for America’s help are questioning the Pentagon’s ability to meet their needs.

Conflicts in Ukraine and Israel have required some logistical backing and filling with uncertain end dates for planners.

In January, the Pentagon dipped into a little-known stockpile earmarked for Israel to help Ukraine meet its urgent need for artillery ammunition to continue its nearly year-old fight against Russian invaders.