 Complete the following phrase:  By 1971, the 231st had a role in both federal and state support with its participation in the DC National Guards Task Force Blue. This mission enabled the 231st to provide civil support to the District of Columbia during times of civil disturbance or to aid the Metropolitan Police Department by being deputized for other events. The 231st took part in various civil missions, including the 1961 Nikita Khrushchev visit to the United States, the 1963 