On 28 June-8 July, Frontex, the European Border and Coast Guard Agency, led an international operation against serious and organised cross-border crime in Central and South Eastern Europe.

The operation, known as Joint Action Day (JAD) Danube 4 focused on combatting the smuggling of migrants and document fraud. It was co-led by Austria, where a coordination centre was put in place to support the exchange of intelligence among the participants. Bulgaria, Croatia, Greece, Hungary, the Netherlands, Romania, Slovenia, Bosnia-Herzegovina, North Macedonia, Montenegro and Serbia also took part in the action. EU agencies and international organisations, such as Europol and Interpol provided the opportunity for real-time operational information exchange between the countries.

Within less than two weeks, the international cooperation led to: