A month later, both the Soviet Union and East Berlin began blocking any further passage of East Germans into West Berlin and erected barbed wire fences, which were quickly upgraded to the Berlin Wall, around the city. Kennedy's initial reaction was to ignore this, as long as free access from the West to West Berlin continued. This course was altered when West Berliners had lost confidence in the defense of their position by the United States. Kennedy sent Vice President Johnson and Lucius D. Clay, along with a host of military personnel, in convoy through East Germany, including Soviet-armed checkpoints, to demonstrate the continued commitment of the U.S. to West Berlin.