President Donald Trump is making a dangerous bet in Europe. This month, the United States announced that it was canceling the deployment of a long-range precision strike battalion to Germany and withdrawing some 5,000 troops from the country. It also abruptly canceled a rotational 4,000-to-5,000-strong combat team bound for Poland, following the earlier cancellation of a similar deployment to Romania in 2025. (The White House has suggested that new forces may still go to Poland but has not specified whether those would come from the United States or be redirected from Germany.) This week, European allies have told media that the Pentagon has informed NATO that it will shrink the forces Washington would rapidly deploy to Europe in a crisis—that is, in the event of a Russian attack on alliance territory. At the same time, the Trump administration has sought to reassure allies that its commitment to Europe’s defense remains undiminished, pledging to sustain the nuclear umbrella over NATO.…