Nato has traded barbs with Russia’s Vladimir Putin after he accused the alliance of moving its military assets closer to the Russian border.
Mr Putin said Russia must strengthen its own capabilities in response.
Nato then defended its actions as “defensive, proportionate” and “in line with our international commitments”.
A spokeswoman told Reuters: “NATO has deployed 4,000 troops to the eastern part of the Alliance to deter any possible aggression.
“These troops cannot compare to the divisions deployed by Russia. In contrast, Russia has troops in Ukraine, Georgia and Moldova against the wishes of their governments.”
Mr Putin, who had been speaking at a press conference with his Finnish counterpart, also accused Nato of refusing to discuss with Russia rules for military flights.
The Western military alliance later denied this, saying that it had discussed air safety in the region at the Nato-Russia Council.
The exchange between Mr Putin and Nato came on the same day as the UK said two of its jets in Romania were scrambled after a suspected Russian aircraft approached Nato airspace over the Black Sea.
There have been long-standing tensions between Nato and President Putin over Russia’s annexation of Crimea in 2014.
Relations deteriorated again in recent months after the poisoning by nerve agent of a former Russian double agent and his daughter in the UK earlier this year.
The UK and the US – both Nato members – say Moscow was behind the attack, although Russia denies it.