Europe's leaders have long known the region is living beyond the means of its aging, stagnant economy. The question is whether the ructions created by Donald Trump's second White House term mean they will do something about it.

Less than a month after the president was sworn in, the continent's once staunch U.S. ally declared it was done paying to keep the peace in Europe. Trump, said Defense Secretary Pete Hegseth, "will not allow anyone to turn Uncle Sam into 'Uncle Sucker.'"

But if Europe must now shoulder the cost of its own defense — right at a time when on its eastern flank Russia is waging war with Ukraine — that risks blowing apart budgets that are already struggling to fund the welfare states that are often seen as the envy of the world.