Ukraine's defense minister said on Sunday that NATO countries were delivering weapons to his country to equip it to fight separatists and "stop" Russian President Vladimir Putin.
Valery Heletey told a news conference he had discussed weapons deliveries in bilateral meetings with NATO defense ministers during a NATO summit in Wales on Sept. 4-5.
NATO officials have said it will not send "lethal assistance" to non-member Ukraine but member states may do so.
Earlier this month, a senior Ukrainian official said Kiev had agreed on the provision of weapons and military advisers from several members of the U.S.-led alliance. Four of the five countries named, including the United States, denied this.
"We reached agreements in closed talks, without media, about ... those weapons that we currently need," said Heletey, who said Ukraine needed weapons "that could stop Putin".
"I have no right to disclose any specific country we reached that agreement with. But the fact is that those weapons are already on the way to us - that's absolutely true, I can officially tell you," he said.
Heletey claimed about 3,500 Russian troops were now on Ukrainian territory with a further 25,000 massed on the Russian side of the joint border.
Moscow denies accusations by Kiev and its Western backers that it has sent troops and tanks into eastern Ukraine to support separatists in a conflict with Ukrainian forces that has killed more than 3,000 people.
A ceasefire negotiated by envoys from Ukraine, Russia, the separatists and Europe's OSCE security watchdog has been in place in eastern Ukraine since Sept. 5.
It is broadly holding despite regular but sporadic violations, especially in key flashpoints such as Donetsk.