Answer based on context:

The dissolution of the Soviet Union in December 1991 brought an end to the Cold War and created the opportunity for bilateral relations with the New Independent States  as they began a political and economic transformation. The United States recognized the independence of Armenia on December 25, 1991, and opened an embassy in the capital city of Armenia, Yerevan in February 1992. The United States has made a concerted effort to help Armenia and other NIS during their difficult transition from totalitarianism and a command economy to democracy and open markets. The cornerstone of this continuing partnership has been the Freedom for Russia and Emerging Eurasian Democracies and Open Markets  Support Act, enacted in October 1992. Under this and other programs, the United States to date has provided nearly $2 billion in humanitarian and technical assistance for Armenia. On March 27, 2006, Armenia signed a Millennium Challenge Compact with the United States; the agreement entered into force on September 29, 2006. Provided the Armenian Government makes progress on mutually agreed-upon policy performance criteria , the agreement will provide $235 million to Armenia over five years to reduce rural poverty through the improvement of rural roads and irrigation networks. In 2012 or 2013, the United States and Armenia are planning to hold their first-ever joint military drills, during which Armenian soldiers will be trained for their current multi-national peacekeeping operations. According to the 2016 U.S. Global Leadership Report, 42% of Armenians approve of U.S. leadership, with 31% disapproving and 27% uncertain.

Which was signed last the Freedom for Russia and Emerging Eurasian Democracies and Open Markets Support Act or the Millennium Challenge Compact?
Millennium Challenge Compact