An armored personnel carrier travels in rebel territory near the village of Torez in eastern Ukraine on Wednesday. Ukraine said it is bracing for further hostilities in the region after NATO said Russia had been sending military aid to separatists. (Menahem Kahana/Agence France-Presse via Getty Images)

NATO’s top commander accused Russia of sending troops and weapons into Ukraine on Wednesday, as Ukrainian officials announced that they were bracing for a return to hostilities in the eastern part of the country that already have claimed more than 4,000 lives.

The accusation was the Western military alliance’s most direct charge against Russia since the start of a tenuous and repeatedly violated cease-fire Sept. 5, and it seemed to signal a decisive abandoning of hopes that the agreement would continue to hold.

U.S. Air Force Gen. Philip M. Breedlove told reporters in Bulgaria that NATO had observed “Russian tanks, Russian artillery, Russian air defense systems and Russian combat troops” enter Ukraine across a “completely wide-open” border with Russia in the previous two days.

A spokesman for the Russian Defense Ministry, Maj. Gen. Igor Konashenkov, swiftly dismissed NATO’s accusations, saying “no facts” existed to back them up.

The assertion that Russia is pressing into Ukraine came as Russian Defense Minister Sergei Shoigu announced plans to project Russia’s military reach even farther, by sending long-range bombers on regular patrol missions along Russia’s borders and over areas from the Arctic Ocean to the Caribbean and the Gulf of Mexico.

“We have to maintain a military presence in the western part of the Atlantic and the eastern part of the Pacific Ocean, in the waters of the Caribbean and in the Gulf of Mexico,” Shoigu said Wednesday.

Breedlove’s accusation is only the latest alarm NATO and its allies have sounded about Russian military activity along and across the Ukrainian border.

The accusation reinforces claims by the Organization for Security and Cooperation in Europe that convoys of weapons and military systems have been moving west through eastern Ukraine in the past few days.

Ukrainian officials, who accused Russia of sending troops and tanks over the border last Friday, are readying the military for attacks in the disputed east.

On Wednesday, Ukrainian Defense Minister Stepan Poltorak told Ukrainian government officials that the country’s forces are deploying to eastern Ukraine and preparing for winter combat because of an increase in activity that has been noted among separatist militias.

Miroslav Rudenko, a representative of the separatists’ self-
proclaimed Donetsk People’s Republic, said Wednesday that separatist forces had no plans to attack the Ukrainian military, accusing Kiev of “planning an offensive operation” that the rebels had to be “ready to rebuff,” according to the Russian news service Interfax.

Speaking in Bulgaria, Breedlove said he was “not sure” about the intent behind sending troops and weapons from Russia into Ukraine but surmised that the goal is to solidify the pro-Russian separatists’ territorial holdings.

“It is our first guess that these forces will go in to make this a more contiguous, more whole and capable pocket of land in order to then hold onto it long-term,” Breedlove said, according to a transcript of his remarks.

Tensions in Ukraine have risen quickly since the Nov. 2 elections in the country’s rebel-held eastern territories. Ukrainian President Petro Poroshenko said last week that those elections had jeopardized “the entire peace process.”