DONETSK, Ukraine -- The scruffy rebels who normally wander about the headquarters of the separatist Donetsk People's Republic were mostly out of view on Friday, replaced by a disciplined new faction who showed up a day earlier with an armored personnel carrier and anti-aircraft gun.
The separatists' so-called prime minister said nothing has changed -- but something has clearly shifted in Ukraine's troubled east.
The balance of power in the region has teetered wildly this week. After Ukrainians elected Petro Poroshenko as the country's president and Russia said it would respect the vote, hopes rose for a resolution to the conflict between the central government and the insurgents who want Donetsk to be part of Russia.
But a day later, the rebels launched an exceptionally bold assault, seizing Donetsk's airport. Ukraine's military responded with previously unseen ferocity, launching airstrikes and sending in paratroopers to retake the airport.
To some, the rebel operation looked like a desperate last stand. But on Thursday, insurgents shot down a Ukrainian military helicopter, killing 12 soldiers, including a general. The same day, the murky Vostok Battalion militiamen took over rebel headquarters in the 11-story Donetsk regional administration building, demanding it be evacuated because of what they said was the presence of looters.
The Vostok Battalion's wrath was ostensibly about the ransacking of a supermarket during the battle for the airport, but some interpreted their move as a power grab.
The battalion is believed to consist largely of Russians, bolstering fears that Russia is either directing the unrest in the east or supporting it in order to destabilize the country and seize regions bordering Russia.
Donetsk insurgency leaders were at pains to stress that the takeover of their building did not signify a change of guard.
"No coup has taken place. The whole terrible panic that was whipped up over this, what you might call a police operation, is a panic that has been instigated by our so-called friends in Kiev," said Alexander Borodai, the self-styled prime minister of the Donetsk People's Republic.
The heavy contingent of Vostok Battalion militiamen had disappeared by Friday morning, as had the armored personnel carrier and vintage anti-aircraft gun. Inside, however, many members of the militia group were spotted in civilian clothing.
Meanwhile, there were mixed signals Friday on whether Moscow and Kiev were moving toward improving relations, a key element in resolving the conflict.
At talks in Berlin, Ukraine said it ordered a $786 million payment to Russia in a first step toward paying off its gas debts, and another round of talks aimed at resolving the two countries' gas price dispute was set for Monday.
Russia has stepped up pressure on Ukraine over gas, demanding payment up front for deliveries starting in June. It has threatened to restrict supplies starting Tuesday if no payment is made.
Moscow has put Kiev's gas debt since November at $3.5 billion, and the CEO of Russian gas company Gazprom said this week that gas delivered in May could raise that to $5.2 billion. Ukraine, which saw gas discounts granted by Russia eliminated following the February ouster of pro-Russian President Viktor Yanukovych, has sought a price agreement before paying up.
Moscow, meanwhile, fired a new legal salvo at Kiev. A spokesman for Russia's top investigative body, Vladimir Markin, said a criminal case had been opened on whether to charge Ukrainian authorities and servicemen with war crimes for the government's offensive against insurgents throughout the east. Russia has repeatedly denounced the operation as a war against Ukraine's own people and demanded that forces be withdrawn from the east.
In Washington, the White House announced that President Barack Obama plans to meet Wednesday in Poland with Poroshenko, Ukraine's president-elect. Obama's European trip includes a stop in Normandy to attend events marking the 70th anniversary of the Allied landing. Russian President Vladimir Putin also plans to be in Normandy, but the White House said Obama has no plans for any formal or one-on-one meeting with the Russian leader, even though they will be at the same events.
Also Friday, the Organization for Security and Cooperation in Europe said it lost contact with a five-member observer team in eastern Ukraine, where four members of another OSCE mission are still being held by pro-Russian rebels.
The OSCE said in a statement that it lost contact with the team, which includes four international workers and a Ukrainian translator, in the Luhansk region late Thursday. The OSCE has been out of contact with another four-member team in the neighboring region of Donetsk since Monday.
An insurgent leader in Donetsk confirmed Thursday that the four-member team was in rebel custody. The rebels told journalists they would "deal with this and then release them," but didn't elaborate or give a specific time frame. The OSCE's teams are in Ukraine to monitor the security situation following Russia's annexation of Crimea and the rise of the pro-Russia separatist insurgency in the east.