Ukraine's protest leaders have named ministers they want to form a new government following the overthrow of President Viktor Yanukovych.
Meanwhile, Russia has put troops on high alert in a show of strength.
President Vladimir Putin's order to 150,000 troops to be ready for war games near Ukraine was the Kremlin's boldest gesture yet after days of posturing since its ally Mr Yanukovych was ousted at the weekend.
Russia denied that the previously unannounced drill in its western military district was linked to events in its neighbour but it came amid a series of increasingly strident statements about the fate of Russian citizens and interests.
With the political turmoil hammering Ukraine's economy, the central bank said it would no longer intervene to shield the hryvnia currency, which tumbled 4% today and is now down a fifth since 1 January.
In Kiev, leaders of the popular protests that toppled Mr Yanukovych named former economy minister Arseny Yatseniuk as their choice to head a new interim government.
In a display of people power, the so-called 'Euromaidan' council made its announcement of Mr Yatseniuk, and candidates for several other key ministries, after its members addressed crowds on Independence Square.
Oleksander Turchinov, now acting president, said the new government would have to take unpopular decisions to head off default and guarantee a normal life for Ukraine's people.
The Euromaidan council's proposals have to be approved by parliament, which meets tomorrow in an atmosphere heavy with memories of recent bloodshed, whose hundred or so victims are taking on the status of martyrs.
The council named career diplomat Andriy Deshchytsya as foreign minister.
Oleksander Shlapak, a former economy minister and former deputy head of the central bank, was named as finance minister.
Andriy Paruby, head of the "self-defence" force protecting the Kiev protest zone from police action during the three months of conflict, was named secretary of the powerful National Security and Defence Council.
"This is a government which is doomed to be able to work only for three to four months ... because they will have to take unpopular decisions," Mr Turchinov said.
In Crimea, thousands of ethnic Russians, who form the majority in the region, demonstrated for independence.
They scuffled with rival demonstrators supporting the new Kiev authorities.
The Crimea is home to part of Russia's Black Sea Fleet, which Russia said it was taking steps to secure.
One person died in the Crimea protest, apparently of a heart attack during a crush of the crowd, Interfax news agency reported.
A Reuters correspondent on the scene reported surging crowds and scuffles but no major violence.
NATO defence ministers, meeting in Brussels, issued a statement supporting "Ukrainian sovereignty and independence, territorial integrity, democratic development, and the principle of inviolability of frontiers".
Their statement made no direct mention of the Russian war games.
US Secretary of State John Kerry said Russia should respect the territorial integrity of Ukraine and be "very careful" in its judgements toward its neighbour.
"What we need now to do is not get into an old, Cold War confrontation," he said on MSNBC television.
Russia has repeatedly expressed concern for the safety of Russian citizens in Ukraine, using language similar to statements that preceded its invasion of Georgia in 2008.
"In accordance with an order from the president of the Russian Federation, forces of the Western Military District were put on alert at 1400 [10am Irish time) today," Interfax news agency quoted Russian Defence Minister Sergei Shoigu as saying.
Mr Shoigu also said Russia was also "carefully watching what is happening in Crimea" and taking "measures to guarantee the safety of facilities, infrastructure and arsenals of the Black Sea Fleet," in remarks reported by state news agency RIA.
Since Mr Yanukovych's downfall on Friday, all eyes have been on Mr Putin, who ordered the invasion of neighbouring Georgia in 2008 to protect two self-declared independent regions with many ethnic Russians and others holding Russian passports, and then recognised the regions as independent states.
Any military action in Ukraine, a country of 46 million people that has close ties with European powers and the United States, would be far more serious - the closest the West and Russia have come to outright confrontation since the Cold War.
Arrest warrant for Yanukovych issued
Meanwhile, Ukrainian authorities have put Mr Yanukovych on the international wanted list.
Prosecutor-general Oleh Makhnytsky said Mr Yanukovych is wanted for "mass murder" connected with the shooting deaths of protesters during the crisis.
The government says it believes he is hiding in Crimea.
It wants him tried at the International Criminal Court in the Hague.
Follow RTÉ's Tony Connolly in Crimea on Twitter @tconnellyRTE