NATO will be escalating its military deliveries to Ukraine despite Kiev not being part of the alliance. The deliveries will include anti-tank and anti-aircraft systems and ammunition to Ukraine, NATO Chief Jens Stoltenberg said Sunday.

"We are stepping up [assistance] with more air defense systems, more anti-tank systems, ammunition, and we do that to... help Ukraine to uphold its right for self-defense," Stoltenberg claimed in an interview with CNN.

Despite upping aid to Kiev in the face of Moscow, Stoltenberg noted that the alliance does not see Russia as an imminent threat to its security, though accused the Kremlin of having "more aggressive" actions.

"We don't see an imminent threat [to NATO], but we see a much more aggressive Russia, which is contesting core values for our security when it is using force against Ukraine but also threatening a balance," he told the US media outlet.

NATO still supported Ukraine's aspirations for accession, the alliance's chief said Sunday but noted that the decision could only be made only through a consensus.

He also told Russia, whose security concerns pushed it to demand NATO to block Ukraine from becoming a member, to "keep in mind that it is up to Ukraine to decide if it wants to join the bloc or not."

Russia had for months been warning of the threat posed against it by NATO's attempts to expand eastward, which happened simultaneously with an increase in NATO military activity along Russia's borders, and batches of lethal weapons being sent to Ukraine, prompting Russia to request security guarantees from the West. Washington failed to provide the guarantees. 

After the West did not respond to Russia's demands, and amid Ukrainian shelling on the Donetsk and Lugansk People's Republics, President Vladimir Putin initiated a special military operation in Donbass.