SAN FRANCISCO — National Guard troops repeatedly rehearsed their role in an operation at a Los Angeles park intended as a show of force against undocumented people and those protesting the Trump administration's immigration crackdown, a deputy commanding general testified Tuesday. Maj. Gen. Scott Sherman, who commanded Guard troops in Los Angeles, was testifying at a trial to determine whether the Trump administration violated the Posse Comitatus Act when it deployed the soldiers and U.S.