The declaration was signed by NATO Secretary General Jens Stoltenberg and the presidents of the European Commission and the European Council, Ursula von der Leyen and Charles Michel, TASS reported.
The sides have not yet made the declaration public.
Earlier, AFP reported, citing the document, that the European Union and NATO intend to give a boost to defense cooperation against the backdrop of the conflict in Ukraine.
According to AFP, the document said the two sides are committed to taking the partnership "to a higher level" and mobilizing "all available common instruments, whether political, economic or military, to achieve common goals".