Barreto agreed to a minor-league contract with the Nationals on Thursday, Jon Heyman of the New York Post reports.
Barreto was released by the Astros on Tuesday, Brian McTaggart of MLB.com reports.
Barreto was reassigned to minor-league camp Saturday, Chandler Rome of the Houston Chronicle reports.
Barreto (elbow) will start at second base and bat ninth Monday in the Astros' Grapefruit League game against the Cardinals, Chandler Rome of the Houston Chronicle reports.
Barreto (elbow) signed a minor-league contract with the Astros on Tuesday that includes an invite to big-league camp, Martin Gallegos of MLB.com reports.
Barreto elected free agency after clearing waivers last week, Taylor Blake Ward of HomePlateView.com reports.
Barreto (elbow) cleared waivers and was outrighted off the Angels' 40-man roster Friday, Sam Blum of The Athletic reports.
Barretto will miss 10 to 12 months following Tommy John surgery, Rhett Bollinger of MLB.com reports.
Barreto (elbow) was placed on the 60-day injured list Wednesday.