Journalists and other observers on November 7 reported seeing dozens of military vehicles, including tanks and armored personnel carriers, entering separatist-controlled areas of eastern Ukraine from Russia. The Organization for Security and Cooperation in Europe (OSCE) confirmed the sightings the following day.
Numerous videos of the convoy have appeared online.
Moscow has denied Russia is involved in the fighting and has called for all parties to observe the Minsk agreement. The separatists claim that the convoys are merely reinforcements being moved toward Donetsk from other parts of the breakaway region.
Pro-Kremlin analyst Sergei Markov, however, told the Daily Beast that Moscow is providing "multilayered support" to the separatist movement.
What is the cause of the renewed military activity in eastern Ukraine?
Here are a few possibilities:
On November 2, the separatist authorities in eastern Ukraine held disputed elections that Kyiv, the OSCE, the EU, and the United States said were illegitimate and a violation of the Minsk agreement. Ukrainian President Petro Poroshenko said the voting "torpedoed" the Minsk process.
In response, Poroshenko sent additional troops to the region and asked parliament to repeal a law on autonomy for the breakaway regions that was passed as part of the Minsk process.
"I think the recent transfer of equipment [from Russia to the separatists] is primarily defensive at this stage," said Tom Frear, a researcher at the European Leadership Network (ELN), in a written interview. "The rhetoric coming out of Kyiv following the elections in the Donbass and the revocation of the autonomy agreement means that Russia and the Donbas leadership can't rule out a renewed Ukrainian offensive."
The influx of equipment to the separatists could also signal a desire to solidify their positions and make some small local gains that could make it easier to get through the winter.
The separatists may be seeking control of specific objects, such as a power plant to the north of Luhansk and Donetsk airport, Frear says. Such moves, he says, are "aimed at securing economic assets that make the long-term survival of the Luhansk People's Republic [LNR] and the Donetsk People's Republic [DNR] more plausible."
Russian analyst Markov also told the Daily Beast that the separatists are seeking to take control over "Piski, Avdiivka, and Schastye, a town with a central heating station." In addition, he speculated they might want to recapture Slovyansk and Kramotorsk, which are "symbolically and strategically important towns for them."
Building A Land Bridge
More dramatically, Moscow may be intent on adding territory to the separatist region that would give Russia a land bridge across eastern Ukraine to the Black Sea peninsula of Crimea, which Moscow annexed in March.
The region is currently accessible to Russia only by air and across the Black Sea and the Sea of Azov. Such a land bridge would make it much easier for Moscow to supply Crimea.
Ivan Lozowy, an independent policy analyst based in Kyiv, says establishing this land bridge is Putin's "unfinished business in eastern Ukraine" and "a priority" for him.
It would, however, have to include the key city of Mariupol, which would be a difficult objective to capture.
Mariupol "is pretty much dead set against letting the Russian troops through," Lozowy says. "The local residents have even been helping to build fortifications."
And What About Kharkiv?
The so-called Novorossia project has foundered in recent months, and could be strengthened if the separatists were able to get control of Kharkiv, Ukraine's second-largest city.
Lozowy notes that the city has "symbolic significance," as well as being a major industrial center.
In December 1917, Kharkiv was the first Ukrainian city to recognize the Bolshevik coup in Russia, and the city served as Ukraine's capital until 1935. Ukraine's largest tank producer is located in the region, among many other military-industrial enterprises.
"Undoubtedly, Kharkiv, which has remained on the whole indifferent to calls to join 'Novorossia,' really upsets certain circles both in Moscow and in the LNR and DNR," Russian military analyst Aleksandr Golts told openrussia.org on November 10.
Lozowy says achieving the two goals of establishing a land bridge to Crimea and incorporating Kharkiv into the separatist territory would "bring Putin and the Kremlin very close to their original goal of building -- or carving out, rather -- a 'Novorossia' from Ukrainian territory."
Robert Coalson, Radio Free Europe Radio Liberty