During an extraordinary meeting of the NATO-Ukraine Commission on Monday, Secretary General of NATO Jens Stoltenberg reaffirmed the alliance’s support for Ukraine and continued the group’s call for Russia to cease its support of pro-Russian rebels. The statement from Stoltenberg comes on the same day the Kiev government asked for lethal military aid from NATO should the situation in East Ukraine deteriorate. Stoltenberg immediately dismissed the request for weapons, saying there was “no military solution to the crisis in Ukraine” but NATO would offer nonlethal aid to help Ukraine reform its military.

“We call on Russia to stop its support for the separatists immediately, to stop destabilizing Ukraine and to respect its international commitments,” said Stoltenberg. “NATO continues its full support for Ukraine's sovereignty, independence and territorial integrity within its internationally recognized borders.”

The meeting comes amid a period of intense fighting in East Ukraine, with an uptick in violence from both sides and a large offensive from pro-Russian rebels, who are now allegedly in control of Donetsk airport and have begun an assault on the city of Mariupol in south Ukraine. So far the conflict has claimed more than 5,000 lives since it began in April 2014.

Ukrainian interior minister Arsen Avakov wrote on his Facebook page Monday that more than 30 people have died in Mariupol since it was attacked over the weekend. The assault on the city may be an attempt to create a land bridge between the Russian border and the annexed peninsula of Crimea, now part of Russia. Mariupol is around 300 kilometers (200 miles) from Crimea and just over 50 kilometers (30 miles) from the Russian border.

However, under questioning from journalists at a press conference Monday, Stoltenberg said it was too early to speculate that pro-Russian rebels were attempting to create a land bridge.