as a political union, the EU has no border disputes with neighboring countries, but Estonia has no land boundary agreements with Russia, Slovenia disputes its land and maritime boundaries with Croatia, and Spain has territorial and maritime disputes with Morocco and with the UK over Gibraltar; the EU has set up a Schengen area - consisting of 22 EU member states that have signed the convention implementing the Schengen agreements or "acquis" (1985 and 1990) on the free movement of persons and the harmonization of border controls in Europe; these agreements became incorporated into EU law with the implementation of the 1997 Treaty of Amsterdam on 1 May 1999; in addition, non-EU states Iceland and Norway (as part of the Nordic Union) have been included in the Schengen area since 1996 (full members in 2001), Switzerland since 2008, and Liechtenstein since 2011 bringing the total current membership to 26; the UK (since 2000) and Ireland (since 2002) take part in only some aspects of the Schengen area, especially with respect to police and criminal matters; nine of the 13 new member states that joined the EU since 2004 joined Schengen on 21 December 2007; of the four remaining EU states, Romania, Bulgaria, and Croatia are obligated to eventually join, while Cyprus' entry is held up by the ongoing Cyprus dispute
Serbia with several other states protest the US and other states' recognition of Kosovo's declaration of its status as a sovereign and independent state in February 2008; ethnic Serbian municipalities along Kosovo's northern border challenge final status of Kosovo-Serbia boundary; several thousand NATO-led Kosovo Force peacekeepers under UN Interim Administration Mission in Kosovo authority continue to keep the peace within Kosovo between the ethnic Albanian majority and the Serb minority in Kosovo; Serbia delimited about half of the boundary with Bosnia and Herzegovina, but sections along the Drina River remain in dispute
