American military aid to Ukraine is faltering. Can Europe pick up the slack?

"European countries are trying to manage an increasingly dangerous situation from an unsustainable peacetime defense and industrial posture," Justin Bronk wrote for the Royal United Services Institute, a U.K. think tank. NATO is "heavily dependent" on the United States for everything from ammunition to satellite capabilities. If America withdraws its aid, or is forced to divert its resources to the Pacific, "Europe will be left vulnerable." With the exception of Poland, though, most European democracies have failed to keep their promises of increased military spending: That's left the continent's stockpiles "badly depleted." Urgent investment is needed, but it will also take time. "It takes years for investment in defense to bear fruit."