MOSCOW (Sputnik) — Earlier in the day, Stoltenberg, European Council President Donald Tusk and European Commission President Jean-Claude Juncker signed the joint EU-NATO leaders' declaration ahead of the opening ceremony of the Alliance's Warsaw Summit.
"This historic decision will enable us to work even closer together and closer than ever before," Stoltenberg said at a press conference.
Neither NATO nor the European Union can address separately a "range of unprecedented challenges" they are facing, the NATO chief added.
The NATO summit is taking place in the Polish capital on July 8-9.