In 1994 amidst widespread fear of illegal immigration in the area, a fourteen-mile fence was constructed on the border between San Diego and Tijuana as part of Operation Gatekeeper, including one in Friendship Park. Border security was tightened in the 1990s and again after the September 11 terrorism attacks in 2001. During that time, people on opposite sides of the border were still able to touch and pass objects through the barrier.