The two-day meeting in Riga comes as concerns mount in Kyiv and Western capitals over Russian troop build-up on the Ukraine border.
NATO foreign ministers are meeting as Russia and the alliance continue to spar over reports of military activity along the Ukraine border.
The United States-headed group has been concerned by Moscow’s massing of troops at the frontier with Ukraine in recent weeks, the second such build-up this year.
Russia, meanwhile, has warned NATO against expanding its military infrastructure in Ukraine.
US Secretary of State Antony Blinken is expected to brief his 29 NATO counterparts on Tuesday about the US intelligence picture on the alliance’s eastern flank and in Ukraine, which is an ally of the security alliance but not a NATO member.
Speaking to reporters in the Latvian capital Riga, Blinken described Russia’s recent military activity as “unusual” and warned any escalatory actions by Moscow would trigger “serious consequences”.
Earlier, NATO chief Jens Stoltenberg labelled Moscow’s troop build-up as “unusual”, but said the alliance had no “clarity” yet regarding Moscow’s intentions.
“We see heavy capabilities, we see armoured units, drones, electronic warfare systems and we see tens of thousands combat-ready Russian troops,” Stoltenberg said on Monday after visiting NATO troops rehearsing battle skills with camouflaged tanks and live rounds in a snowy woodland north of Riga.
Meanwhile, Russian President Vladimir Putin on Tuesday said the expansion of NATO military infrastructure in Ukraine was a red line he hoped would not be crossed, and voiced concern about military drills being held near Russia’s borders.
Speaking at an investment forum in Moscow, Putin also said Russia was also developing a new hypersonic missile that would soon be in its arsenal.
US warns of ‘serious consequences’
Kyiv has previously expressed fears that Moscow might be preparing for an attack.
But Ukraine’s defence minister said on Tuesday that Russia’s latest troop build-up is likely intended to strengthen Moscow’s bargaining position in a future meeting between US President Joe Biden and Putin following their initial meeting in Geneva in June.
In a statement on the economy ministry’s website, Oleksiy Reznikov said relations between Ukraine and Russia were worse when Russia built up troops earlier this year.
In May, Moscow stationed about 100,000 soldiers on the border, the largest number since Russia’s annexation of Crimea in 2014, according to Western officials.
It later ordered those units to pull back, but a renewed build-up has seen some 92,000 soldiers deployed along the frontier again, the head of Ukraine’s military intelligence told the Military Times outlet earlier this month.
Moscow rules out military incursion
Moscow has repeatedly dismissed suggestions from Kyiv and its Western allies that it may be readying to make a military incursion into Ukraine as inflammatory and complained about alleged increasing NATO activity in the region.
On Tuesday, Foreign Minister Sergey Lavrov accused the alliance of deploying a significant amount of military hardware near Russia’s borders and said Moscow could respond to security threats from Western countries and Ukraine if necessary.
Moscow annexed Ukraine’s Crimean Peninsula in 2014 and Russian-backed separatists seized a swath of eastern Ukraine, in regions bordering Russia, that same year.
Ukraine and its Western supporters have accused Russia of sending troops and arms across the border to support the rebel forces in the Donbas. Moscow has routinely denied those claims.