After the fall of the Berlin Wall in 1989, the organization became drawn into the Balkans while building better links with former potential enemies to the east, which culminated with several former Warsaw Pact states joining the alliance in 1999 and 2004. On April 1, 2009, membership was enlarged to 28 with the entrance of Albania and Croatia. Since the September 11 attacks, NATO has attempted to refocus itself to new challenges and has deploy...