WASHINGTON — Retired senior military leaders condemned their successors in the Trump administration for ordering military units on Monday to rout those peacefully protesting police violence near the White House.

As military helicopters flew low over the nation’s capital and National Guard units moved into many cities, Defense Secretary Mark T. Esper and General Mark A. Milley, the chairman of the Joint Chiefs of Staff, publicly aligned themselves behind a president who chose tear gas and rubber bullets to clear peaceful protesters from a park so that he could stage a photo op at a nearby church.

In so doing, Mr. Esper, who described the country as a “battlespace” to be cleared, and General Milley, who wore combat fatigues on the streets of the capital, thrust the two million active-duty and reserve service members into the middle of a confrontation in which the “enemy” is not foreign, but domestic.