Croatia also started a Membership Action Plan at the 2002 summit, leading to a national debate on whether a referendum on NATO membership needed to be held there. Croatian Prime Minister Ivo Sanader ultimately agreed in January 2008, as part of forming a coalition government with the HSS and HSLS parties, not to officially propose one. Montenegro declared independence on 3 June 2006, and the new country subsequently joined the Partnership for Peace programme at the 2006 Riga summit. Albania and Croatia were invited to join NATO at the 2008 Bucharest summit that April, though Slovenia threatened to hold up Croatian membership over their border dispute in the Bay of Piran. Slovenia did ratify Croatia's accession protocol in February 2009, and Croatia and Albania both officially joined NATO just prior to the 2009 Strasbourg–Kehl summit, with little opposition from Russia.