Lublin Triangle

The Lublin Triangle is a regional cooperation initiative bringing together Poland, Lithuania, and Ukraine. It was launched on 28 July 2020 in the Polish city of Lublin, where the foreign ministers — Jacek Czaputowicz (Poland), Linas Linkevičius (Lithuania), and Dmytro Kuleba (Ukraine) — signed a joint declaration creating the format.

The choice of Lublin was symbolic: the city gave its name to the Union of Lublin of 1569, which united the Kingdom of Poland and the Grand Duchy of Lithuania (which then included much of present-day Ukraine and Belarus) into the Polish–Lithuanian Commonwealth. The modern Triangle invokes this shared heritage as a basis for closer ties.

The format's stated objectives include:

• Supporting Ukraine's European and Euro-Atlantic integration, including eventual EU and NATO membership.
• Deepening military, economic, cultural, and infrastructure cooperation.
• Coordinating positions on regional security, particularly regarding Russian and Belarusian policy.
• Defending the sovereignty and territorial integrity of member states within internationally recognized borders, including Ukrainian control over Crimea and the Donbas.

The Triangle gained heightened relevance after Russia's full-scale invasion of Ukraine in February 2022. The three states have used the platform to coordinate sanctions advocacy, weapons transfers, and humanitarian assistance, and to lobby other EU and NATO partners on Ukraine's behalf. Poland and Lithuania have been among the most vocal supporters of accelerated Ukrainian accession to Western institutions.

The Lublin Triangle complements, rather than replaces, other regional frameworks such as the Bucharest Nine (B9), the Three Seas Initiative, and the broader Eastern Partnership. It is a relatively lightweight format — operating through ministerial meetings and joint declarations rather than a permanent secretariat — which gives it flexibility but limits its institutional weight. It is sometimes discussed alongside the Associated Trio (Ukraine, Moldova, Georgia) and proposals for a wider "Quadriga" that would add a fourth partner.