On Friday night, when Russian troops began storming the command center of Ukraine’s air defenses in the region of Crimea, the hundred or so soldiers barricaded inside had orders not to open fire. Half of them locked themselves inside a bunker at the far end of the base, which stretches about 2 km along the Black Sea coast. The other half stood and watched as about two dozen Russian commandos forced their way inside. Their only means of self-defense was to form a human chain behind the main gate, hoping the Russian truck would not drive over them as it rammed its way through the iron bars. “We are not allowed to use our weapons,” says Major Vladimir Yaremchuk, who was at the base that night. “But those guys came here armed to the teeth.”

Standing beside the mangled gate the following day, Yaremchuk told TIME that the Russians were apparently trying to goad them into firing the first shot. “It was a provocation,” he said. “Everyone knows that at first blood, their hands will be untied and that will be the end of it.”

For the Ukrainian troops based in Crimea, that provocation was just the latest in a string of humiliations. They had already been barricaded inside their bases for a week by Russian troops. Many of them had been forced to give up their weapons and had seen the chief of Ukraine’s navy defect to the Russian side. But all these blows to their morale seemed bearable compared with what will happen a week from Sunday, when Crimea holds a referendum on its secession from Ukraine. After that, the region’s several thousand Ukrainian servicemen will find themselves marooned outside their country’s borders. The new government of Crimea will then set out to evict them.

“We want only one thing,” said Sergei Aksyonov, the new pro-Russian leader of Crimea, who was installed after an armed takeover of the regional parliament on Feb. 27. “We want to have no armed men staying here with their guns poking into our sides, because those weapons could, either by accident or through a surge of emotion, start going off. That’s what we do not want,” he told TIME on Sunday. So after the referendum, the Ukrainian soldiers will either have to sign an oath of allegiance to Aksyonov’s government or resign from the Ukrainian military and become civilians. “Those who came here from other regions of Ukraine will be allowed a corridor to leave in peace back to their homes,” Aksyonov said.

But what about the Ukrainian soldiers who were born and raised in Crimea? Hundreds of them face the prospect of either fleeing their home region or going back to their Crimean towns and cities, where the new leadership considers them an occupying force. One of them, a lieutenant colonel of the Ukrainian air force, told TIME last week that he will not take either option. “If they start the siege, we will shoot to kill,” said the 40-year-old officer, who only gave his first name, Andrei, because he fears for the safety of his family in the Crimean city of Yevpatoria, his hometown. “These are not blanks. These are real bullets, and we will use them as our orders prescribe,” he said inside the Belbek air-force base, patting the barrel of his Kalashnikov.

But not all of his fellow officers have the luxury of using one of those. In the nearby command center of Ukraine’s air defenses, a base called A-2355, the soldiers have orders not to fire their weapons. That restriction has given the Russian siege of the base a bizarre dynamic over the past week. It has forced the men of A-2355 to resort to various means of nonviolent resistance, deceptions and stalling tactics, turning their standoff into a battle of nerves.

That battle began peaceably enough last Saturday, March 1, with offers of money in exchange for surrender. At A-2355, which lies on the outskirts of Sevastopol, a group of uniformed officers from the Russian Black Sea fleet arrived to discuss the terms with the base commanders. They didn’t have to travel far. The home of the Black Sea fleet is in Sevastopol, on the southwestern tip of the Crimean Peninsula, and houses at least 13,000 Russian troops and dozens of warships. “At first they came with their chevrons on, all their Russian insignia, and identified themselves as officers of the Black Sea fleet,” says Yaremchuk, who witnessed their arrival. “There were a few of them, all ranked naval captain or higher.” (In the Russian navy, that would mean they were commanders of at least one warship.)

According to four Ukrainian officers interviewed by TIME, the Russians offered unspecified amounts of money if they agreed to defect. At some bases, including A-2355, they also promised defecting officers an equal position in the armed forces of a future Crimean state, which they said would soon split off from Ukraine and become independent. That would suggest they had foreknowledge of the referendum, which was only announced on March 6, at least a week in advance. On March 16, that vote will offer the residents of Crimea two possible futures: either split off from Ukraine and become an independent state, or ask Russia to annex Crimea. Remaining a part of Ukraine is not an option on the ballot.

Some of the Russian negotiators seemed to assume that the annexation of Crimea is inevitable. At Ukraine’s Belbek air-force base, one officer of the Russian Black Sea fleet asked the Ukrainian officers to defect directly to the Russian armed forces. “I guess they skipped a step,” says Viktor Kukharchenko, a colonel stationed at Belbek. “They were operating on the assumption that Crimea was already a part of Russia.”

The first and so far only major defection among the officer corps was announced the following day, March 2. Rear Admiral Denis Berezovsky, who had been appointed as head of Ukraine’s entire navy only two days earlier, told reporters he was renouncing his loyalty to Ukraine and pledging an oath “to the people of Crimea.” His subordinates, however, did not follow his lead, so the Russians were forced to ramp up the pressure.

Across Crimea, thousands of troops began surrounding all the Ukrainian bases and blocking the troops inside. The invaders were dressed like Russian special forces who had taken the insignia off their uniforms. They drove vehicles with Russian license plates and had standard-issue Russian hardware, including Ural trucks, Tigr all-terrain vehicles, Dragunov sniper rifles and Kalashnikov machine guns.

But their lack of insignia allowed Russian President Vladimir Putin to deny his troops were occupying Crimea. His Minister of Defense, Sergei Shoigu, has said he has no idea where they got all that Russian hardware. Aksyonov, the new Crimean Prime Minister, tells TIME that local “self-defense forces” seized it all from Ukrainian bases, then attached Russian military license plates that they somehow purchased. Because of the matching green uniforms and mysterious origins of the invaders, the Ukrainian troops have begun calling them “little green men.”

At air base A-2355, the occupying force demanded that Ukrainians hand over their weapons and surrender, as they did at all the military installations in Crimea. Different officers reacted differently, depending on their orders from Kiev. Those who had enough manpower and equipment to stand a chance were ordered to defend the base by force if necessary. But A-2355 is little more than a radar station, equipped to monitor the air space over Crimea and relay data to antiaircraft batteries. “We’d be fighting against Russian special forces,” says Yaremchuk. “It would be like a heavyweight boxer against a teenager. Sure, we would die with honor. But we would all die.”

So instead of resisting, they hid their cache of weapons in a storage room and invited the Russians inside to inspect the empty armory. Apparently satisfied, the Russian troops left the base alone for nearly a week, returning only on Friday, March 7. “Word somehow reached them that we still had a cache of assault rifles hidden away,” says Yaremchuk. That morning, two Ural trucks full of heavily armed men — about 30 in all — arrived at the base and demanded the surrender of its weapons. The commanding officers obliged, even handing over the two training pistols from the base’s shooting range.

But by evening, the little green men came back, pressed the bumper of their truck against the gate and began ramming through it. It was the first time the Russians had attempted to force their way into a Ukrainian base, and with no means of self-defense, the troops barricaded inside formed a line in front of the gate and stood there as the truck pushed toward them. “They stopped when they saw us standing there,” says Yaremchuk. Instead of plowing right through the gate, the Russians simply climbed over the wall of the base and fanned out across it. The base commanders had meanwhile locked themselves in a bunker and began sending distress signals to their ranking officers. Negotiations began, and by midnight, the Russian forces received orders to withdraw, leaving the Ukrainians as they had found them.

But the end is approaching anyway, as annexation looms. After the referendum, Yaremchuk says he will likely have no choice but to return to his hometown in the region of Zhytomyr, in western Ukraine, where his friends will greet him as a hero for holding out as long as he could. “People there already despise Putin,” he says. “So for me it won’t be so bad.” What worries him is the fate of the officers whose families and homes are in Crimea. “They will be uprooted,” he says. Or forced to live in a hostile land.

Contact us at letters@time.com.