Waving a blizzard of American flags, more than 100 people braved the damp, chilly weather yesterday to march briskly along Constitution Avenue NW, then to Lafayette Square, to show their backing of U.S. policy in the Persian Gulf.

The demonstration was the second rally here in support of U.S. policy over the long holiday weekend. Although it was smaller than Saturday's march, which drew about 500 people, organizers of yesterday's Presidents Day Troop Rally were convinced that they had made a lot more noise.

Shouting "U.S.A." and "Support Our Troops," demonstrators paraded past motorists who leaned on car horns and gave thumbs-up signals. The marchers belted out "God Bless America" and "Born in the U.S.A."

Many of the marchers have relatives and friends in the Persian Gulf, said Robin Breadon, a WPGC-FM radio personality who was the rally's master of ceremonies. Breadon said a videotape of the rally would be sent to troops.

Rally participants did not so much address topical concerns, such as the possibility of ground warfare, as the need to counter images left in the media by anti-war activists.

"What our troops need to see on television is us out here," Tom Wieber, a Vietnam veteran in a black beret, told a crowd that had the enthusiasm of a high school pep rally.

George Morgenthaler, an off-duty White House police officer who wore a yellow ribbon and U.S. flag on his jacket, joined in the applause in Lafayette Square. "I think there's a lot of negative things being broadcast about protests against the war," he said. "We need to show the troops people are supporting it."

Watched over by U.S. Park Police in front of the White House, some marchers exchanged heated words with a group of peace activists whose opposition to U.S. policies has become known by the steady beat of their drums.

Michael Austin, an Army reservist, was on the side of those who rallied for the troops. He has four relatives in the Persian Gulf. Austin said he does not favor war, but he supports the U.S. commitment.

"I'll support that commitment in any way I can," he said.