BELBEK, Ukraine — Russian soldiers on Tuesday fired warning shots at a group of Ukrainian soldiers who marched unarmed toward their heavily equipped counterparts in an attempt to reclaim their airbase that had been seized a day earlier. The column of some 100 Ukrainian military pilots, led by Col. Yuli Mamchur, stopped their advance at Pokryshkin airbase in Belbek, in Ukraine's Crimea region, only after the Russians trained their rifles on the group.

The soldiers remained there — under the close watch of Russian elite forces armed with machine guns rifles and mortars and blocked by military jeeps — throughout the afternoon as negotiations between Mamchur and a man known only as "Roman" took place behind Russian lines.

“They [Russian soldiers] told us: ‘Stop. Do not come closer. We have orders to shoot,’” said Andriy Matchenko, deputy head of logistics for the Belbek. “They said they would shoot at our legs if they needed to stop us.” No one was hurt, but the tense standoff highlighted the growing tensions on the semi-autonomous Crimean peninsula, where Russian military forces have effectively taken control.

The warning shots mark the first time that weapons have been fired since Russia moved thousands of troops into Crimea.

Col. Yuri Mamchur, commander of the Ukrainian garrison at the Belbek air base, lead his men to the base outside Sevastopol, Ukraine, Tuesday, March 4, 2014. Russian troops, who had taken control over Belbek airbase, fired warning shots in the air as around 300 Ukrainian officers marched towards them to demand their jobs back. Image: Ivan Sekretarev/Associated Press

Beginning last week, troops in unmarked fatigues swarmed military bases here, issuing ultimatums to Ukrainian troops to lay down their arms and swear their allegiance to the Crimean people and to Russia, or else face military storms by the heavily armed groups. As negotiations were underway, Russian President Vladimir Putin pulled back 150,000 troops who had been conducting military exercises in western Russia near the border with Ukraine, in what appeared to be an attempt to calm tensions with the West, which has strongly condemned its actions in Crimea. During Putin's press conference on Tuesday afternoon, there was no acknowledgement of what is widely believed — and certainly appears to be — a Russian invasion of Crimea. The president emphatically denied that the troops on the ground here were Russian, citing the fact that they are wearing uniforms with no insignia. Several troops willing to speak to Mashable acknowledged that they were Russian, but did not outrightly say they were Russian military forces. However, the military vehicles they arrived in had Russian license plates. As the officers at the Belbek base waited for news of a solution to the stalemate, many of them phoned their wives to let them know they were fine. Several wives had spent the previous night next to the compound gates to "keep up morale," one of them, named Tanya, told Mashable. "Bunny, I love you. We are good here," one of the men said, as his comrades whistled and hollered.

Russian soldiers, meanwhile, held their positions atop grassy bluffs and tucked behind concrete barriers. All that was visible were their eyes, their forest green helmets and rifle barrels. From time to time, a driver would turn over the engine of one of the jeeps, sending the Ukrainian troops into a frenzy. Around 2 p.m. local time there was still no resolution, and both sides seemed to be growing restless. Fearful of potential provocations, Mamchur marched his men back to their barracks, where they remained on alert late Tuesday night. "We are all here now. The mood is intense but also calmer, and there is still no answer from the Russian side," Alexey Khramov, a military press officer at the base told Mashable late Tuesday. "Only time now will tell us what will happen."