Ukrainian and Western officials are worried that a Russian military build-up near Ukraine could signal Moscow’s plans to invade its former Soviet neighbor.
The Kremlin insists they have no such intention and has accused Ukraine and its Western supporters of claiming to hide their own alleged aggressive designs.
It is unclear whether the Russian troop concentration foreshadows an imminent attack or represents an attempt by Russian President Vladimir Putin to persuade the United States and its NATO allies to refrain from sending troops and weapons to Ukraine and drop plans for its possible integration into NATO.
Here’s a look at the current tensions:
What are the roots of the conflict between Russia and Ukraine?
Russia annexed Ukraine’s Crimean peninsula in 2014 after its pro-Moscow president was ousted by mass protests. Weeks later, Russia threw its weight behind a separatist uprising that broke out in eastern Ukraine.
Ukraine and the West accused Russia of sending its troops and weapons to support the rebels. Moscow denied this, accusing the Russians of joining the separatists of volunteering.
More than 14,000 people have died in the fighting that devastated the eastern industrial heart of Ukraine, known as the Donbas.
A peace agreement from 2015 mediated by France and Germany helped end large-scale fighting, but attempts to reach a political settlement have failed and sporadic skirmishes have continued along the tense line of contact.
Earlier this year, an increase in ceasefire violations in the east and a Russian troop concentration near Ukraine fueled fears of war, but tensions eased as Moscow withdrew most of its forces after maneuvers in April.
The latest Russian military build-up
Ukraine complained this month that Moscow has kept about 90,000 troops not far from the two countries’ borders after massive war games in western Russia during the autumn.
The Ukrainian Ministry of Defense said that units from the Russian 41st Army have stopped near Yelnya, a city about 260 kilometers north of the Ukrainian border.
The Commander-in-Chief of the Ukrainian Armed Forces, Lieutenant General Valeriy Zaluzhny, said that Russia also has about 2,100 troops in the rebel-controlled East and that Russian officers hold all command positions in the separatist forces. Moscow has repeatedly denied the presence of its troops in eastern Ukraine.
Kyrylo Budanov, head of Ukraine’s military intelligence service, claimed in a weekend interview with the Military Times that Moscow was preparing an attack from several quarters, including Russia’s ally Belarus, in late January or early February.
Russia has not provided any details on the number and location of its troops, saying that their deployment on its own territory should not affect anyone.
What does Moscow want?
The Kremlin has accused Ukraine of not respecting the 2015 peace agreement and criticized the Western world for not encouraging Ukrainian compliance. The agreement was a diplomatic coup for Moscow, which demands that Ukraine give broad autonomy to the rebel regions and offer a comprehensive amnesty to the rebels.
Ukraine, in turn, has pointed to breaches of the ceasefire by Russia-backed separatists and the continued presence of Russian troops in the rebel east – accusations that the Kremlin has denied.
In the midst of the accusations, Russia has rejected a four-way meeting with Ukraine, France and Germany and said that it is pointless given Ukraine’s refusal to follow the 2015 agreement.
Moscow has strongly criticized the United States and its NATO allies for supplying Ukraine with weapons and conducting joint exercises, and says it encourages Ukrainian hawks to try to retake rebel-held areas by force.
Earlier this year, Putin ominously said that a military attempt by Ukraine to retake the rebel in the east would have “serious consequences for the Ukrainian state.”
The Russian leader has repeatedly claimed that Russians and Ukrainians are “a people” and accused large parts of Ukrainian territory of being historic parts of Russia – arbitrarily granted to Ukraine by communist leaders under the Soviet Union.
Putin has strongly emphasized that Ukraine’s efforts to join NATO represent a red line for Moscow, and also expressed concern over plans by some NATO members to set up military training centers in Ukraine. He said it would give them a military foothold there even without Ukraine joining NATO.
“They can place anything there under the guise of a gym,” Putin said last month. “Formal membership in NATO may never come, but the military development of the territory is already underway.”
Is the threat of a Russian invasion real?
Russia dismissed talk of an invasion plot as a Western smear campaign, accusing the allegations of concealing a Ukrainian intent for an attack in the east. Ukraine denies such plans.
US officials acknowledged that Moscow’s intentions were unclear, but pointed to Russia’s past behavior as a cause for concern.
In a speech to Ukraine’s foreign minister this month, US Secretary of State Antony Blinken said Putin’s “game book” was to build forces near the border and then invade, “and falsely claimed that (Russia) was provoked.”
Some observers interpret the build-up of troops as a demonstration by Putin that Russia is ready to step up its efforts to persuade NATO to respect Moscow’s red lines and stop sending troops and weapons to Ukraine.
Last week, Putin noted with satisfaction that Moscow’s warnings had finally taken some drag and caused “some stress” in the West. He added: “It is necessary to keep them in that state for as long as possible so that it does not occur to them to arrange any conflict at our western borders that we do not need.”
He urged Russian diplomats to push for “serious long-term guarantees that guarantee our security in this area because Russia can not continue that way, constantly thinking about what might happen there tomorrow.”
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