The article has been developed in the frame of the project ‘Promoting Order at the Edge of Turbulence (POET)’that is conducted in the Center for International Studies and Development (CISAD) at the Jagiellonian Universityin Krakow (Poland). The project is co-financed by the Polish National Agency for Academic Exchange under theNAWA Guest Professorship programme and the Polish National Agency for Academic Exchange within theNAWA Chair programme. The author wishes to acknowledge the financial assistance of the NAWA Grant(PPN/PRO/2020/1/00003/DEC/1) from the Polish Academic Exchange Council and NCN grant(ZARZADZENIE NCN 94/2020) from the Polish National Science Council. Bibliogr. s. 889-890

The Three Seas Initiative (TSI) is a forum of Baltic, Black and Adriatic sea countries. In 1919, pioneering British geopolitical theorist Halford J. Mackinder promoted a ‘Middle Tier’ strategy, that paralleled the Polish interwar ‘Intermarium’ project. Today, the United States views the TSI as an asset in the ‘New Europe’, while pro-Atlanticist Central and Eastern European states see it as a tool to build transatlantic connections. This article suggests that the TSI revives Mackinder’s ‘Middle Tier’ strategy. Similar to how the Franco–British bonds with the ‘Middle Tier’ states sought to offset Germany and Russia a century ago, today stronger ties between the US and the ‘New Europe’ within the TSI strengthen the position of NATO vis-à-vis the EU, rebalance Western EU actors and counter Russian interests.