"The situation is very serious, it's critical and it's urgent and therefore I fully support the new attempts by Chancellor (Angela) Merkel and President (Francois) Hollande to find a political solution," Stoltenberg said, Censor.NET reports citing AFP.
Stoltenberg, speaking on arrival at the Munich Security Conference, said the Russian-backed rebels in eastern Ukraine had made large gains in recent weeks with the help of a substantial increase in supplies.
Russia continues supporting the separatists, it continues to destabilize the situation in Ukraine, ignoring the sovereignty and territorial integrity of Ukraine, he added.
Stoltenberg stressed that Russia must respect the international law. He noted that they cannot be rewritten or broken. He called on Russia to change its course and find a peaceful solution to the problem, Evropravda reports.
There have been growing calls in Washington to supply Kyiv with weapons to push back the rebels and Stoltenberg was asked if there should be such military pressure.
He did not answer directly, instead saying that NATO was doing two things - offering full political and practical support for Ukraine, while also beefing up its own military resources.
Today, before her visit to Moscow, Merkel stated that she was not sure that the talks with Putin regarding the Donbas will provide results. Deputy Head of the Presidential Administration of Ukraine Valerii Chalyi said that the basis of negotiations between Ukrainian President Poroshenko, Merkel and Hollande was the Minsk Agreement, and not Putin's document.