The Slovenian opposition to Croatia's accession ambitions is warranted by fears that Zagreb's demands, as presented in individual negotiating chapters, may seek to predetermine the outcome of the two countries' border dispute. The most important factor underlying the Slovenian veto, and simultaneously the essence of the Slovenian-Croatian border spat, is the question of the Piran Bay's ownership and delimitation of the mutual border in the north Adriatic. Although a sea-border feud about a minute area, it has major consequences for the Croatian accession process, indirectly affecting the EU's 'open door policy' and potentially exerting an adverse influence on integration with the EU by other countries in the Western Balkans.