WASHINGTON (Reuters) - The United States military expects to start training Ukrainian trainers on using the Howitzer artillery system in coming days, a senior U.S. defense official said on Monday.

       The official, speaking on condition of anonymity, said the training would take place outside Ukraine.

       The United States has previously trained Ukrainian forces in the United States on the Switchblade drone.

       (Reporting by Idrees Ali and Kanishka Singh)