Abstract. The Three Seas Initiative has become highly important in connection with the geopolitical transformations of the Central and Eastern Europe. Not only is the number of participants expanding, but also extra-regional actors with similar values are being involved in consultations. In addition to the Initiative's association with infrastructure projects, including new north-south transport corridors, the military dimension of cooperation is becoming increasingly clear. Many projects have dual purpose and, in addition to economic goals, serve to increase the mobility of NATO armies. One of the tasks is to unite the transport and logistics infrastructure of the countries of NATO's eastern flank and western Ukraine. The lack of necessary funding and a different vision of the organization's purpose by a number of its participants are an obstacle to the implementation of this development logic.