MARIUPOL, Ukraine -- The turmoil in Ukraine dominated the European landscape Thursday, as three protesters were killed in a clash in southern Ukraine, high-level talks were held in Geneva and Vladimir Putin weighed in on his neighbor's future for hours from Moscow.
Still, the constellation of events left the nation of 46 million no closer to solving its essential challenge: the confrontation pitting Ukraine's new government in Kiev against a pro-Russian insurgency in its eastern regions that is being tacitly supported by Moscow.
Three pro-Russian protesters were killed and 13 injured during an attempted raid overnight on a Ukrainian National Guard base in the Black Sea port of Mariupol, Ukraine's authorities said Wednesday .
The Interior Ministry said a mob of around 300 people armed with stun grenades and firebombs were involved in the bloodiest episode to date in the month-long insurgency.
Masked and battle-ready militia bearing sophisticated firearms have been deeply involved in seizing government offices in eastern Ukraine, igniting suspicions that much of the unrest is being stirred with Russia's backing.
But in a four-hour televised question-and-answer session, Putin on Thursday dismissed as "nonsense" claims that Russian special forces were fomenting the unrest in eastern Ukraine.
"It's all nonsense, there are no Russian units, special forces or instructors in the east of Ukraine," Putin said.
He did admit - for the first time - that the troops in unmarked uniforms who had captured Ukraine's Crimean Peninsula before its annexation last month by Moscow were Russian soldiers.
Putin also expressed hope that four-way talks between Ukraine, the U.S., the European Union and Russia in Geneva on Thursday could map a way out of one of Europe's greatest security threats in decades.
Ukraine's Interior Ministry said shots fired by servicemen in the Mariupol base initially proved insufficient to deter the pro-Russian crowd from proceeding with their assault.
There were no casualties among Ukrainian servicemen, the ministry said. At least 63 people involved in the attack were detained, but local media cited police as saying 38 were later released.
The southern Ukrainian city lies on the road running from Russia along the coast to Crimea, the peninsula that Russia annexed last month. NATO says Russia has up to 40,000 troops along its border with Ukraine. If Russia was eyeing a possible "land bridge" from Russia to Crimea, it would need to take over the region that includes Mariupol.
Speaking in parliament, acting President Oleksandr Turchynov said a pro-Russian gang carrying automatic weapons attempted to storm the base three times.
APTN footage filmed outside the base on Wednesday night showed an unidentified man coming out to speak to masked men in the crowd armed with assault rifles. He told them the military had asked for 10 minutes to think over an unspecified ultimatum.
The masked men insisted they wanted no bloodshed. A short while later, however, a crowd of mainly masked young men armed with bats and sticks began throwing Molotov cocktails at the base's gate and at the trucks parked in front of it. Sounds of gunfire were heard in response.
One soldier involved in the battle, a 20-year old conscript who gave his name only as Stanislav, said troops were forced to act in self-defense.
"We were attacked by unidentified people and we didn't want to shoot, but they were behaving aggressively," he told the AP. "At first we fired in the air, but they continued advancing."
One protester admitted to a hospital with a bullet wound to the stomach said soldiers opened fire on them while they were attempting to force open the gates.
"We just threw Molotov cocktails to light the way," said Sergei Shevchenko, a 40-year-old businessman from the regional capital, Donetsk.
Nearby residents were divided about the night's events.
"Russia isn't just exporting oil and gas, but also terrorism," said 43-year-old resident Yevgeny Nechiporenko. "This shooting and blood, the blood is on Russia's hands."
Yet passers-by berated Nechiporenko as he spoke, with one accusing him of being an "agent of the West."
"We are willing to give up our lives so long as we don't have to serve the fascists from Kiev," said resident Anna Govorko.
The skirmish came after the government announced an operation to retake control of Slovyansk, a city close to the Russian border that has emerged as the focal point of the armed insurgency, and government buildings in several other cities in the east.
Elsewhere in Mariupol, where pro-Russian protesters have been occupying city hall for nearly a week, 150 people rallied in front of the building, which is now encircled by barricades of tires and barbed wire.
Spotting a television crew, 26-year-old protester Yelena Gorgeyeva got to her knees and declared "Putin, save us, I implore you!"
German Mandrakov, a pro-Russian protester who described himself as acting chief of the city council, said pro-Russian protesters went to the military base Wednesday evening to "convince them to switch to people's side."
Crowds have blocked or attacked other troops in eastern Ukraine.
On Wednesday, hundreds of people in Kramatorsk, 15 kilometers (9 miles) south of Slovyansk, encircled a column of Ukrainian armored vehicles carrying several dozen troops. Soon after, masked gunmen in combat gear arrived and Ukrainian soldiers surrendered the vehicles to them.
Turchynov told parliament on Thursday the brigade that handed over its vehicles would be disbanded and its members put on trial.
At another location near Kramatorsk, a crowd also surrounded troops on 15 Ukrainian armored vehicles. To end the standoff, Ukrainian servicemen handed over the magazines from their assault rifles to pro-Russian militia. The infantry vehicles were allowed to return to their base in Dnipropetrovsk, 225 kilometers (140 miles) away.
In Moscow, Putin denounced the Ukrainian authorities' decision to use the military to uproot the protests in the east as a "grave crime." He added he told his Western counterparts urging him to help disarm pro-Russian protesters that the Ukrainian government should first pull the army back.
"They are sending tanks, armored personnel carriers and cannons there!" he said. "Have they gone nuts?"
Nataliya Vasilyeva in Kiev and Vladimir Isachenkov in Moscow contributed to this report.