Turkey's candidacy to join the EU has been a matter of major significance and considerable controversy since it was granted in 1999. Turkey has had historically close ties with the EU, having an association agreement since 1964,[19] being in a customs union with the EU since 1995 and initially applying to join in 1987. Only after a summit in Brussels on 17 December 2004 (following the major 2004 enlargement), the European Council announced that membership negotiations with Turkey were officially opened on 3 October 2005.