The last time tanks paraded through the streets of Washington, the U.S. Army was at the peak of its confidence and power.

U.S. forces had smashed Saddam Hussein’s army in a ground assault that lasted just 100 hours. The Soviet Union was months from collapse.

Three decades later, Army tanks are once again preparing to take to the streets of the capital, this time as part of a procession that President Trump has described as a celebration of the Army’s 250th birthday and raw American firepower. Now, though, the service is working through its most profound identity crisis since its defeat in Vietnam.

There are concerns about the politicization of the force by a president who describes protesters as “animals” and often seems to be looking for an excuse to mobilize ground troops in response to demonstrations or civil unrest.

There are big questions about whether the Army’s aging equipment can survive on future battlefields swarming with cheap precision drones and what role the service will play as the Pentagon shifts its focus to deterring China.