Following the breakup of Yugoslavia in 1991, Slovenia and Croatia became independent countries. As the border between the countries had not been determined in detail prior to independence, several parts of the border were disputed, both on land and at the sea, namely in the Gulf of Piran.
According to the Croatian Bureau of Statistics, the two countries share about of border. According to the Statistical Office of the Republic of Slovenia, the border spans . The border mostly runs along a southwest-northeast axis.
The countries have attempted to resolve the dispute, most notably with the Drnovšek–Račan agreement in 2001 that was ratified by Slovenia but not by Croatia. Because of the disputed border, Slovenia blocked Croatia's EU accession talks until the agreement was reached by both countries and the EU to settle the dispute by a binding arbitration.
On 29 June 2017, the Permanent Court of Arbitration issued a binding ruling on