Ukraine's acting President Olexander Turchynov has reinstated military conscription to deal with deteriorating security in the east of the country.
Turchynov signed the decree on Thursday, the same day pro-Russian militants seized the regional prosecutor’s office in the eastern city of Donetsk.
The decree reinstates the draft for non-exempt Ukrainian men between 18 and 25 years old and cites what it describes as "the further aggravation of the socio-politcal situation" in eastern and southern Ukraine, as well as "blatant aggression" by "illegal" armed pro-Russian groups.
The move comes a day after Turchynov said that his government was "helpless" to quell the growing pro-Russian separatist movement in two eastern regions and could not control its own troops.
Earlier Thursday, pro-Russian protesters stormed the prosecutor's office in the separatist-held city of Donetsk, lobbing stones and smashing windows after accusing the office of working for the Western-backed government in Kyiv.
To shouts of "Fascists", a refrain Moscow uses to describe Ukraine's new government, hundreds of people pelted the police with paving stones and then cornered some, dragging them to the ground and beating them. The police soon surrendered.
Donetsk, a city of about one million people in Ukraine's industrial east, is at the center of an armed uprising across the steel and coal belt by mainly Russian-speakers threatening to secede from Ukraine.
The violence, in a city already largely under the control of separatists, underscored the shifting security situation and suspicions in the region.
"The prosecutor's office was issuing criminal orders from Kyiv against its own people, charging them with separatism and other fake crimes," said one protester, a 43-year-old man from Donetsk who gave his name as Igor.
Pro-Russian separatists in the city have declared a "People's Republic of Donetsk" and say they will hold a referendum on secession on May 11.
Related video report by Arash Arabasadi and Brian Padden:
Russian attache detained for spying
Ukraine also ordered the expulsion of Russia's military attache, saying it had caught him ``red-handed'' receiving classified information on the country's cooperation with NATO during an armed uprising Kyiv said is directed from Moscow.
The Foreign Ministry said on Thursday the diplomat, who has not been named, had been detained a day earlier and declared persona non grata.
Ukraine's security service said he was a Russian intelligence officer who had been collecting intelligence on ``Ukrainian-NATO military and political cooperation.”
There was no immediate response from Moscow, which, like Kyiv, was observing the May 1 holiday.
The crisis in Ukraine will dominate talks between German Chancellor Angela Merkel and President Barack Obama in Washington on Friday, with both leaders keen to show the West is united in its resolve to take even tougher measures against Russia if necessary.
The U.S. and European Union both imposed new sanctions against Moscow on Monday, accusing Russia of failing to implement a diplomatic accord aimed at calming the situation in Ukraine.
Merkel and Obama will discuss at what point further measures - targeting the Russian economy directly - could be taken, senior German officials said.
Members of Russian Trade Unions march during the May Day celebration at the Red Square in Moscow on May 1, 2014.
Russia's May Day Parade
Russia staged a huge May Day parade on Moscow's Red Square for the first time since the Soviet era on Thursday, with workers holding banners proclaiming support for President Vladimir Putin after the seizure of territory from neighboring Ukraine.
Thousands of trade unionists marched with Russian flags and flags of Putin's ruling United Russia party onto the giant square beneath the Kremlin walls, past the red granite mausoleum of Soviet state founder Vladimir Lenin. About 100,000 people took part in the celebration.
Many banners displayed traditional slogans for the annual workers' holiday, such as ``Peace, Labour, May.'
But others were more directly political, alluding to the crisis in neighboring former Soviet republic Ukraine, where Russian troops annexed the Crimea peninsula in March, precipitating the biggest confrontation with the West since the Cold War.
Putin wants troops out of southeast
Also Thursday, Russian President Vladimir Putin told Merkel that the withdrawal of Ukrainian military units from the southeast of the country, ending violence and launching a national dialogue are key issues in the Ukraine conflict, the Kremlin said.
The Kremlin also said that Merkel, in a call it said she initiated, asked Putin to help free seven Organization for Security and Cooperation in Europe (OSCE) military observers who are being held by pro-Russian militia in Ukraine.
Russian Foreign Minister Sergei Lavrov also called for talks between Kyiv and pro-Russian separatists in southeastern Ukraine.
"Russia believes that this dialogue between the authorities in Kyiv and their opponents could be established, or launched in the framework of the Organization for Security and Cooperation in Europe. We hope that our partners, our Western colleagues allow Ukrainians to establish this dialogue without major impediment," Lavrov said.
The prime minister spoke during a visit to Peru.
Thomas Graham, an expert on Russian and Eurasian affairs, said the situation in east Ukraine is difficult to decipher.
"The problem that we have at this point is that everyone thinks someone else controls the situation on the ground,” said Graham, a former U.S. national security official who is managing director at Kissinger Associates Inc.
“And the crisis has moved along far enough that there are a lot of elements on the ground that are acting on their own, without reference necessarily to Moscow, Kyiv, Brussels or Washington,” he said.
“So, the risk of the incidence that leads to widespread violence -- perhaps bloodshed -- can force the hands of people who have postured themselves in ways that they might regret depending on how things play out on the ground in eastern Ukraine."
IMF loan has tough requirements
The director of the IMF's European department, Reza Moghadam, told reporters Thursday that the Washington-based agency expects Ukraine to meet all its financial obligations, even as it teeters on the brink of bankruptcy. That includes $2.2 billion it owes Russia for natural gas purchases.
The IMF announced a $17 billion loan package for Ukraine over the next two years, and the World Bank, the European Union, Japan , Canada and the United States have pledged another $15 billion. The loans come with a requirement that Kyiv undertake economic reforms, including tax hikes, wage freezes and cuts in social aid.
But Moghadam acknowledged that the $17 billion IMF loan is not as big as it appears. He said $5 billion of the figure is meant for Ukraine to pay back money it already owes the IMF from a previous loan.
VOA's Catherine Maddux contributed to this report from Washington. Some information for this report provided by RFE/RL, Reuters, AP
Photo Gallery: Images from Ukraine