YENAKIEYEVE, Ukraine - On a recent spring morning, an important visitor watched Russian-backed rebels conduct infantry maneuvers in eastern Ukraine.

"The general is very pleased," rebel commander Ostap Cherny told his troops, referring to the figure in camouflage encircled by guards.

The man - almost certainly a Russian military officer - became alarmed when he saw two journalists approach. His entourage shielded him - forbidding photos - and the group sped off in a motorcade, the "general" safely inside a black Toyota SUV with no license plates.

Nearly a year into the Ukraine conflict, the extent of Moscow's direct involvement has become clear: They may wear camouflage, but the Russians' presence in eastern Ukraine is hardly invisible.

A tactical shift

At the same time, there has been a tactical shift apparently aimed at minimizing Russia's military presence, part of an effort to persuade the West to lift economic sanctions.

Visits by the Associated Press to training grounds like those near Yenakieyeve and interviews with dozens of rebels reveal that Russian armed forces spearheaded some of the major separatist offensives, then swiftly withdrew.

More recently, as a shaky cease-fire has taken hold, Russia has kept fewer troops in Ukraine but increased rebel training. NATO and an independent London-based Russian scholar estimate that Russia has several hundred military trainers in eastern Ukraine.

Since hostilities began around mid-April last year, the Ukrainian government and the West have accused Moscow of waging an undeclared war in Ukraine by sending thousands of troops to fight with the separatists and providing weaponry.

Kremlin's denial

While the Kremlin acknowledges that many Russians have fought as volunteers, it firmly denies sending troops or arming rebels.

Throughout the conflict and often days before a new flash point, AP reporters would see as many as 80 armored vehicles a day, mostly coming from the direction of the Russian border. Their ultimate origin was impossible to establish.

Separatist fighters confirm that clothing and ammunition are among supplies they receive from Russia.

"Yes, our brothers are supplying us - you know who," one fighter who uses the nom de guerre Taicha said at a checkpoint in the town of Krasny Luch. Most rebels won't reveal their full names for fear of retaliation against their families.

A quick exit

When the town of Debaltseve finally fell to the separatists on Feb. 19 after weeks of fighting over the railroad hub, the true victors were long gone.

"Our friends helped us," said Andrei, a fighter who fought in Debaltseve. Unlike his platoon, which had nothing newer than a T-72 tank, he said the Russians had modern T-90s. Like other rebels, Andrei would not give his last name because his family lives in a Ukraine-controlled area.

Alexei, another fighter, became animated when asked about Russians in the battle for Debaltseve: "I'm not going to hide it: Russians were here. They went in and left quickly."

Igor Sutyagin, a senior research fellow at the Royal United Services Institute in London, has spent months collecting evidence of the Russian presence in Ukraine, coming up with an exhaustive list of combat formations.

The presence of large numbers of Russian troops has been a "permanent feature of the conflict" since August, Sutyagin said, with the number peaking at about 9,000 troops in late February.