As the steadily advancing Ukrainian army sets its sights on reclaiming the largest rebel-held city in eastern Ukraine, tension build as a large Russian army waits across, waiting to step in to protect the separatists, according to Reuters.
President Vladimir Putin has resisted mounting pressure from Russian nationalists to send the army in to back the mutiny in eastern Ukraine, Reuters reported. U.S. and NATO officials say there are now about 20,000 Russian troops massed just east of Ukraine.
Pro-Russian separatists in eastern Ukraine have been fighting the Kiev government since April while Ukraine and Western countries have accused Moscow of backing the mutiny with weapons and soldiers, a claim the Russian government has repeatedly denied, according to Reuters.
The United States and NATO would probably not respond militarily, but the West would be certain to impose major sanctions that would put the shaky Russian economy on its knees and quickly erode Putin's power, according to Reuters.
"When you see the build-up of Russian troops and the sophistication of those troops, the training of those troops, the heavy military equipment that's being put along that border, of course it's a reality. It's a threat, it's a possibility - absolutely," U.S. Defense Secretary Chuck Hagel said Wednesday, Reuters reported.
Polish Prime Minister Donald Tusk said he believed "the threat of a direct intervention (by Russia) is definitely greater than it was a few days ago, or two weeks ago," in regards to Russia's mounting troops on Ukraine's border, according to Reuters.
Adding to the concern is Russia's proposal in recent days for a humanitarian mission to eastern Ukraine, Reuters reported.
"We share the concern that Russia could use the pretext of a humanitarian or peacekeeping mission to send troops into eastern Ukraine," NATO spokeswoman Oana Lungescu said in an e-mailed statement, according to Reuters.
Humanitarian concerns are rising as Ukrainian forces come closer to encircling the city of Donetsk and continue their fight against the pro-Russia rebels in the large city of Luhansk, Reuters reported.
As the Ukrainian military intensified its campaign against the rebels, heavily populated areas have increasingly come under attack, but Ukrainian security spokesman Andriy Lysenko denied Wednesday that Ukrainian airplanes have carried out airstrikes on Donetsk, according to Reuters.
"The cities of Donetsk and Luhansk, as well as other cities and residential areas, are not being bombed by Ukrainian military aviation," Lysenko said, Reuters reported.
