 Complete the following phrase:  At the 1999 Washington summit, where Hungary, Poland, and the Czech Republic officially joined, NATO also issued new guidelines for membership with individualized Membership Action Plans for Albania, Bulgaria, Estonia, Latvia, Lithuania, North Macedonia, Romania, Slovakia, and Slovenia. In May 2000, these countries joined with Croatia to form the Vilnius Group in order to cooperate and lobby for common NATO membership, and by the 2002 Prague summit seven were invited for membership, which took place at the 