Russian President Vladimir Putin speaks Wednesday during a meeting at the Kremlin in Moscow. (Sergei Karpukhin/Reuters)

NATO’s top general and the commander of all U.S. forces in Europe warned Thursday that Russian President Vladimir Putin was “not done” in eastern Ukraine and that the Kremlin probably would continue to use military pressure to influence the future policies of the government in Kiev.

“What smart people are saying is that Mr. Putin is very clear that he does not want Kiev leaning to the West and he will use the appropriate force necessary to keep Kiev from leaning to the West,” Air Force Gen. Philip M. Breedlove said at a news conference at NATO headquarters in Brussels.

Breedlove said that Putin’s activity in eastern Ukraine was carefully orchestrated and the region was well-supplied, noting that the border between eastern Ukraine and Russia was “wide open.”

“We see a force [in eastern Ukraine] that has been trained and is led by Russian leadership and has trained up to the brigade level,” Breedlove said of the separatist forces.

Russia has repeatedly denied that it has any military personnel operating in eastern Ukraine.

Breedlove noted that the Organization for Security and Co-operation in Europe has reported that at least 7,000 fighters have flowed from Russia into eastern Ukraine since the start of the conflict last year.

When pressed on the accuracy of the number, Breedlove said that the figure was not so much accurate as it was an indication that “there’s a constant flow of [troops and equipment] across the border.”

Breedlove also stressed that the Russians have developed a sophisticated logistics chain to the separatists, noting that NATO had monitored at least 30 major resupply operations since the start of the conflict.

While uniformed Russian forces remain encamped near the Russia-Ukraine border, Breedlove specified that NATO had not seen a change in troop levels in recent months. He did note that NATO had observed Russia “stocking important supplies, ammunition, etc., to levels that would support operations.”

“Mr. Putin has developed a very capable force along the periphery of Ukraine,” Breedlove said.

More than 6,000 people have died since hostilities began in Ukraine last year, with both sides violating the Minsk Agreement cease-fire that was signed in February.

When asked at a news conference Thursday why NATO had yet to call the cease-fire a failure, NATO Secretary General Jens Stoltenberg said it remains “the best possible foundation for a peaceful solution.”

Breedlove’s remarks came toward the end of a five-day trip by Secretary of Defense Ashton B. Carter to Europe, where he reassured NATO of the U.S. commitment to the alliance, pledging equipment and forces for new initiatives.