There were three rounds of eastward expansion by NATO. The Czech Republic, Poland and Hungary joined in 1999. In 2004, Estonia, Latvia, Lithuania, Bulgaria, Romania, Slovakia and Slovenia became members. Croatia and Albania acceded to NATO in 2009. Russia sees these accessions as violating previous agreements. The US and NATO consider the enlargement rounds as being in accordance with the NATO–Russia Founding Act – a memorandum of understanding under international law that primarily regulates cooperation on issues of security.