The warning comes a day after Russian troops, using armoured vehicles, automatic weapons and stun grenades, seized the last military facilities under Ukrainian control in Crimea, the Black Sea peninsular that Russian President Vladimir Putin formally annexed on Friday.
“The (Russian) force that is at the Ukrainian border now to the east is very, very sizeable and very, very ready,” NATO’s Supreme Allied Commander Europe, US Air Force General Philip Breedlove, told an event held by the German Marshall Fund think-tank.
Russia’s seizure of Crimea, which has a majority Russian population, after the ousting of Ukraine’s pro-Russian president by mass protests has triggered the worst East-West crisis since the Cold War.
The United States and the European Union have targeted some of Putin’s closest political and business allies with personal sanctions and have threatened broader economic sanctions if Putin’s forces encroach on other eastern or southern parts of Ukraine with big Russian-speaking populations.
Breedlove said NATO was very concerned about the threat to Transdniestria, which declared independence from Moldova in 1990 but has not been recognised by any United Nations member state. About 30 percent of its half million population is ethnic Russian, which is the mother tongue of an overall majority.
Russia launched a new military exercise, involving 8,500 artillery men, near Ukraine’s border 10 days ago.
“There is absolutely sufficient (Russian) force postured on the eastern border of Ukraine to run to Transdniestria if the decision was made to do that, and that is very worrisome,” Breedlove said.
The president of ex-Soviet Moldova warned Russia last Tuesday against considering any move to annex Transdniestria, which lies on Ukraine’s western border, in the same way that it has taken control of Crimea.
The speaker of Transdniestria’s parliament had urged Russia earlier to incorporate the region.
Russia’s Deputy Defence Minister Anatoly Antonov was quoted by the state’s Itar-Tass news agency on Sunday as saying that Russia was complying with international agreements limiting the number of troops near its border with Ukraine.
Moscow’s ambassador to the European Union, Vladimir Chizhov, also told Britain’s BBC television on Sunday that Russia did not have any “expansionist views”.
Asked to give a commitment that Russian troops would not move into other Ukrainian territory outside the Crimea, Chizhov said: “There is no intention of the Russian Federation to do anything like that.”
US Senator John McCain, a Republican foreign policy specialist, told the same BBC show that Putin’s actions in Ukraine were akin to those of Adolf Hitler in 1930s Germany.
“I think he (Putin) is calculating how much he can get away with, just as Adolf Hitler calculated how much he could get away with in the 1930s,” McCain said.
McCain criticised the international response and said he supported sending military equipment to Ukraine. He also said he considered Moldova and the Baltic nations, all former Soviet states with sizeable Russian populations, to be under threat.
US President Barack Obama’s national security adviser said on Friday that the world was reassessing its relationship with Russia and Washington was sceptical of Russian assurances that troop movements on the Ukraine border were no more than military exercises.
Belarussian President Alexander Lukashenko, a close ally of Russia, accepted on Sunday that Crimea was now “de facto” a part of Russia, but he criticised the annexation as a “bad precedent”.
Speaking to reporters in Minsk, Lukashenko said Ukraine, which shares a long land border with Belarus, should remain “a single, indivisible, integral, non-bloc state”.
Hopes that the limited sanctions measures in place might dissuade further incursions were dealt a blow on Sunday when Russia’s SMP bank, whose main shareholders were targeted by US sanctions, said Visa Inc and MasterCard Inc had resumed payment services for its clients.
The bank said it was glad the two biggest international payments systems had listened to its arguments to reverse Friday’s suspension of services as it was wrong to target the bank, which was not itself the target of any sanctions.
Putin and Russian media had mocked the sanctions, which did not stop the Russian military completing its takeover of Ukraine’s military bases in Crimea.
Russia’s defence ministry said on Sunday that its flag was now flying over 189 Ukrainian military installations on the peninsula.
A referendum held a week ago after Russian troops had seized control of Crimea overwhelmingly backed union with Russia but was denounced by Washington and the European Union as a sham.
The EU emphasised its support for the new pro-Western government in Kiev, signing a political agreement with interim Prime Minister Arseniy Yatseniuk last week.
They also promised financial aid for the government – which Moscow says came to power by a coup to overthrow Russian ally Viktor Yanukovich – as soon as Kiev reaches a deal with the International Monetary Fund.
The IMF is to report next Tuesday on advanced talks with Ukraine on a loan programme that would be linked to far-reaching reforms of the shattered economy.
Three months of protests were set off by Yanukovich’s refusal to sign an association agreement with the EU, the political part of which was signed on Friday.