NATO will supply Ukraine's military with secure communication equipment this month, its head Jens Stoltenberg told President Petro Poroshenko at a meeting on Thursday called to discuss an escalation of Kiev's conflict with Moscow.
Stoltenberg praised Ukraine's "calm and restraint" after Russia seized three of its naval vessels and their crew off Crimea last month.
Part of a 40 million euros ($46 million) pledge by the Western military alliance to strengthen Ukraine's armed forces, Stoltenberg said the secure communications equipment would be delivered by the end of the year.
The NATO chief reiterated support for the former Soviet nations' aspirations to join the alliance - a plan which Moscow vehemently opposes.
Russia is resisting international calls to release the ships and men seized in the Kerch Strait, which controls access to the Sea of Azov near the Crimea region that Moscow annexed from Ukraine in 2014.
"Ukraine invites allies to come up with comprehensive, tough measures to respond to Russia's actions," Poroshenko told reporters at a joint briefing.
EU leaders will discuss Ukraine and Russia over a summit dinner later in the day.
The bloc's leaders are expected to offer Ukraine help for regions affected by Russia's actions in the Azov Sea but stop short of imposing further sanctions on Russia, something sought by more hawkish governments.