Where and in which year were troops reactivated after Vietnam?

The reactivation of troops after the Vietnam War specifically refers to the period when the U.S. military began to increase its presence and readiness in Europe due to the changing geopolitical landscape leading up to the end of the Cold War. Mannheim, Germany, in 1989 is the correct answer as this establishment was part of the efforts to bolster U.S. forces in Europe and support NATO allies in a time of transition in Eastern Europe, particularly with the fall of the Berlin Wall that year.

The significance of this location and date is noted in military history as a response to evolving strategic needs following the Vietnam conflict. The re-emergence of activities in Europe helped prepare U.S. forces for potential operations, underlining a new military focus that emerged as the Cold War tensions shifted. Thus, Mannheim and the year 1989 represent a pivotal moment in U.S. military history after Vietnam, focusing on readiness and strategic positioning in Europe.