We're adding updates throughout this post as the day continues.
David Mdzinarishvili /Reuters/Landov
Flags fly outside the Crimean parliament building in Simferopol on Thursday during a rally by pro-Russian protesters. Gunmen seized government buildings in the city.
Flags fly outside the Crimean parliament building in Simferopol on Thursday during a rally by pro-Russian protesters. Gunmen seized government buildings in the city. David Mdzinarishvili /Reuters/Landov
Tensions continue to rise in Ukraine, where months of public protests led last week to the downfall of President Viktor Yanukovych's government. His opponents are now installing pro-Western ministers to replace the pro-Russian leaders who worked for Yanukovych. The interim government is expected to be in charge at least until new elections can be held, perhaps in late May.
Meanwhile, in the Crimea region there have been clashes between the ethnic-Russian majority and those who want Ukraine to remain united. Now, there's a standoff in the Crimean capital of Simferopol, where pro-Russian gunmen have taken over government buildings. Local lawmakers there on Thursday set a provisional date in May for what they hope will be a vote giving the region more autonomy.
World leaders are watching closely to see how Russia reacts. Already, President Vladimir Putin has put his military on alert. Diplomats from the U.S. and European Union have urged Russia not to do anything that might further inflame the situation. Defense Secretary Chuck Hagel said Thursday that the U.S. is "closely watching" Russia's military movements. Russian Foreign Minister Sergei Lavrov said he and Secretary of State John Kerry had talked about cooperating in an effort to end the crisis.
White House spokesman Jay Carney on Thursday said the U.S. welcomes the Ukrainian parliament's efforts to install new leadership and stabilize the nation. He said Yanukovych had "abdicated his responsibility."
— "Dozens of heavily armed gunmen seized control of local government buildings in Ukraine's Crimea region early Thursday and raised the Russian flag, mirroring the three-month protest movement that drove Ukraine's pro-Russian president into hiding last week." (The Associated Press) There were no reports of injuries at the sites in Simferopol, the local capital. Ukrainian security forces established a security perimeter around the area.
As the Parallels blog has written, Crimea "is an autonomous part of Ukraine, [that has] strong emotional ties to Russia and [where] a majority of people identify themselves as Russian.
Update at 9:15 a.m. ET: "The Crimean parliament has said it wants to hold a referendum on greater self-rule. Such a vote would be a challenge to the new powers in the Ukraine capital Kiev, the BBC's Mark Lowen reports from the Crimean regional capital Simferopol."
"A provisional date for the referendum has been set as May 25, which coincides with the early Ukrainian presidential and city mayoral elections, the Crimean Information Agency said, citing the chairman of the Supreme Council of Crimea, Vladimir Konstantinov." (RT.com)
— Viktor Yanukovych, who last weekend was removed from the president's post by Ukraine's parliament, issued a statement saying he still considers himself to be his nation's leader. He also said that because of "threats of bodily harm ... I'm forced to ask the Russian authorities to ensure my personal security against the actions of extremists." (RT.com)
Ukrainian officials have said they want to arrest Yanukovych and charge him with mass murder for the deaths of more than 80 anti-government protesters last week in Kiev.
There were reports Thursday that Yanukovych might be in Russia. Officials there have agreed to ensure his personal safety, Russian news agencies reported. (Voice of America)
Update at 11 a.m. ET: Yanukovych is expected to hold a news conference on Friday in the southern Russian city of Rostov-on-Don, RIA Novosti reports.
— Russian fighter jets were patrolling the airspace on their side of the border with Ukraine, and Russia's military remained on alert. "Constant air patrols are being carried out by fighter jets in the border regions," Interfax reported, quoting a Russian ministry statement. "From the moment they received the signal to be on high alert, the air force in the western military region left for the ... air bases." (Reuters)
— Ukraine's acting president, Oleksandr Turchynov, "warned that any move by Russian troops off of their base in Crimea 'will be considered a military aggression.' " (AP)
— NATO Secretary-General Anders Fogh Rasmussen urged Russia "not to take any action that could escalate tension or create misunderstanding."
— U.S. Defense Secretary Chuck Hagel said Thursday that he is "closely watching Russia's military exercises along the Ukrainian border." Speaking in Brussels, Hagel also said that "I expect Russia to be transparent about these activities, and I urge them not to take any steps that could be misinterpreted, or lead to miscalculation during a very delicate time — a time of great tension." (Update at 8:30 a.m. ET, via Reuters.)
— Kerry, Lavrov Talk: "Russia said that U.S. Secretary of State John Kerry proposed cooperation with Moscow to resolve the Ukraine crisis during a telephone conversation with Foreign Minister Sergei Lavrov on Thursday," Reuters reports. (Update at noon ET.)
Ukraine's New Government
— Ukraine's parliament was working to form a new coalition government. According to Reuters, the lawmakers "agreed on Thursday the country should be led by a coalition government and proposed former economy minister Arseny Yatseniuk to lead it as prime minister."
Update at 7:55 a.m. ET: The AP just moved this bulletin — "Ukraine parliament approves Arseniy Yatsenyuk as new prime minister."
Update at 1:50 p.m ET: "The White House is welcoming the efforts by Ukraine's parliament to stabilize the country," the AP writes, and says ousted President Viktor Yanukovych 'abdicated his responsibility.' Press secretary Jay Carney says Yanukovych left a 'void' that Ukraine's lawmakers are trying to fill."
We've previously summed up what sparked months of protest in Kiev and ultimately led to Yanukovych's dismissal this way:
"The protests were sparked in part by the president's rejection of a pending trade treaty with the European Union and his embrace of more aid from Russia. Protesters were also drawn into the streets to demonstrate against government corruption."