B9

The Bucharest Nine (commonly abbreviated B9) is a consultative platform of nine NATO member states located along the alliance's eastern flank. It was established on 4 November 2015 in Bucharest at the initiative of Romanian President Klaus Iohannis and Polish President Andrzej Duda, with the aim of coordinating positions on Euro-Atlantic security ahead of NATO summits.

The nine members are: Bulgaria, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, and Slovakia. All nine joined NATO after the end of the Cold War — the Czech Republic, Hungary, and Poland in 1999; the remaining six in 2004.

The format operates primarily through summits of heads of state, supplemented by meetings of foreign ministers and parliamentary speakers. It does not have a permanent secretariat or treaty basis; it is an informal consultative grouping rather than a formal regional organization. Decisions are non-binding and intended to feed into NATO's collective decision-making process.

Core themes addressed by the B9 have included:

• Strengthening NATO's deterrence and defence posture on the eastern flank
• Implementation of decisions taken at the Warsaw (2016), Brussels (2018, 2021), Madrid (2022), and Vilnius (2023) NATO summits
• Response to Russian military activity, particularly after the 2014 annexation of Crimea and the 2022 full-scale invasion of Ukraine
• Support for Ukraine and for the open-door policy of NATO enlargement

US engagement with the format has been significant: President Joe Biden participated in a virtual B9 summit hosted by Romania in March 2022, shortly after Russia's invasion of Ukraine. Subsequent summits, including the one held in Warsaw in February 2023, have featured high-level US participation.

The B9 is often discussed alongside other sub-regional formats such as the Three Seas Initiative and the Nordic-Baltic Eight (NB8), though its remit is narrower and explicitly focused on NATO-related security matters.