WASHINGTON — Nearly a year after about 200 people were charged with rioting during President Trump’s inauguration, federal prosecutors announced they would drop a majority of the cases because they could not prove the defendants planned or participated in protests with the aim of smashing storefronts, setting fires and causing other property damage.

The U.S. Attorney’s Office in the District of Columbia said it was dismissing charges against 129 people awaiting trial. Prosecutors said they would move ahead with cases against the 59 who they say were directly involved in the riots.

In a court filing, prosecutors said they plan to focus on “the core group that we believe is most responsible for the destruction and violence that took place on Inauguration Day.”

The decision comes about a month after a District jury acquitted the first six people to go to trial on rioting charges stemming from the Jan. 20, 2017, celebration. Lawyers for those defendants argued they were lawfully protesting while others in the group peeled off to vandalize businesses and vehicles.

The prosecutors’ decision, announced late Thursday, was applauded by supporters of the protesters who have argued the government overreached in its response.