European nations want to spend big on artillery, missiles and drones, but costly military pension commitments risk constraining those ambitious plans, according to previously unreported NATO-member defense budget data compiled by Reuters.

NATO's European members are rushing to ramp up spending on military hardware as a bellicose Russia threatens their eastern flank and U.S. President Donald Trump's long-term commitment to European security appears suddenly in doubt.

But for over a dozen NATO members, pensions make up a large — and largely overlooked — chunk of their defense budgets.