(VOVworld) - Former Norwegian Prime Minister Jens Stoltenberg took office as NATO Secretary General on Wednesday in Brussels.

New NATO Secretary General Jens Stoltenberg

In his first press conference after the swearing-in ceremony, Stoltenberg called on Russia to change its political attitude and behavior in Eastern Europe, specifically in Ukraine. He said NATO is ready to resume a constructive relationship with Russia.

Describing the crisis in Ukraine as a major threat to NATO security, Stoltenberg pledged to continue "full support" for an independent Ukraine with territorial integrity and stability.

Stoltenberg said NATO will not confront Russia but will never compromise on the principles that the military alliance set in Article 5 of the Washington Treaty on collective defense.