It has taken two weeks for Crimea to slip from Ukrainian control and into Russia's grasp.
The peninsula was "gifted" to Ukraine in 1954 by then-Soviet leader Nikita Khrushchev, a largely symbolic administrative shift for fellow republics of the USSR.
It became an autonomous region of Ukraine in 1992, and continues to be dominated by ethnic Russians.
Here are some of the key events so far in the run-up to an historic, if controversial, referendum scheduled for Sunday.
February 27:
Armed commandos storm the Crimean parliament and other government buildings, raising the Russian flag.
Lawmakers decide there will be a referendum on the status of Crimea on May 25 -- the date set for presidential elections across Ukraine.
Officials say 61 of the 64 parliamentarians present voted in favour, but the claim cannot be verified because gunmen barred independent observers from entering.
March 1:
Ukraine says thousands of extra Russian troops have been sent to Crimea, where they take up positions at strategic sites, including the airports of the region's capital, Simferopol, and in Sevastopol, where Russia's Black Sea fleet is headquartered.
Armed men are also controling vehicles on the main highway into the peninsula from mainland Ukraine, effectively cutting it off.
The pro-Russian authorities bring forward the date of their referendum to March 30.
The newly-chosen prime minister of Crimea, Sergiy Aksyonov, asks Russian President Vladimir Putin for help to ensure "peace and calm" on the peninsula.
In Moscow, Putin wins parliamentary approval to deploy troops in Ukraine
March 2
Pro-Kremlin forces lay siege to Ukrainian military facilities in Crimea and Ukraine's navy chief Denis Berezovsky switches allegiance to the breakaway authorities of Crimea.
March 3
Ukranian border guards say troops are continuing to pour in to Crimea.
Moscow says deposed Ukrainian president Viktor Yanukovych is still the legitimate head of state, even if his authority is "negligible".
March 5
Russian forces take partial control of two Ukrainian missile sites.
The Organization for Security and Co-operation in Europe (OSCE) says it is sending 35 military observers to Ukraine. The group will try unsuccessfully three times to get into Crimea.
March 6
The Crimean parliament tells Russian President Vladimir Putin they want the peninsula to become part of Russia.
They bring forward the date of the referendum again, to March 16, and say voters will be given the option of joining Russia or "signficant strengthening of their autonomy within Ukraine".
Lawmakers also sanction the creation of the post of Crimean defence minister and announce that Ukrainian forces stationed in Crimea will be considered "occupying forces" and treated accordingly.
March 7
Russia's parliament says it will respect the "historic choice" that Crimea makes in its referendum.
Moscow says OSCE observers barred from entry to Crimea did not get the required permission from the local authorities.
March 8
OSCE observers turn back again from Crimea, after shots are fired. No one is injured.
March 9
Russian President Vladimir Putin tells Western leaders the separatist government of Crimea is legitimate and "is taking actions based on international law and with the aim of guaranteeing the legitimate interests of the population of the peninsula".
Russia offers an economic carrot, saying it will give $1.1 billion in aid to Crimea "to support the development of the industrial and economic infrastructure of Crimea".
March 10
While Washington still refuses to recognise the weekend referendum, its ambassador to Kiev says the US would support greater autonomy for Crimea as long as this does not happen "under the barrel of a gun".
March 11
German Chancellor Angela Merkel says Crimea has been "annexed".
Lawmakers in Crimea vote for full independence from Ukraine. Russia's foreign ministry says the declaration is "absolutely lawful."
Pro-Moscow officials in Crimea launch a website for the referendum with a Russian domain name, while armed men take control of air traffic control in Simferopol, banning flights anywhere other than Moscow.
March 12
The G7 group of leading nations says the Crimean referendum will have "no legal effect" and threatens action if Moscow does not back down.
Ukrainian Prime Minister Arseniy Yatsenyuk meets US President Barack Obama at the White House.
MARCH 13
Washington warns Russia it is preparing a "very serious" response together with Europe to the Crimea vote.
Russia sends fighter jets to Belarus in response to a request by the country's president, after NATO beefed up its presence in light of the crisis in Ukraine.
Ukraine's parliament votes to create a new National Guard of 60,000 volunteers.
It has taken two weeks for Crimea to slip from Ukrainian control and into Russia’s grasp.
The peninsula was “gifted” to Ukraine in 1954 by then-Soviet leader Nikita Khrushchev, a largely symbolic administrative shift for fellow republics of the USSR.
It became an autonomous region of Ukraine in 1992, and continues to be dominated by ethnic Russians.
Here are some of the key events so far in the run-up to an historic, if controversial, referendum scheduled for Sunday.
February 27:
Armed commandos storm the Crimean parliament and other government buildings, raising the Russian flag.
Lawmakers decide there will be a referendum on the status of Crimea on May 25 — the date set for presidential elections across Ukraine.
Officials say 61 of the 64 parliamentarians present voted in favour, but the claim cannot be verified because gunmen barred independent observers from entering.
March 1:
Ukraine says thousands of extra Russian troops have been sent to Crimea, where they take up positions at strategic sites, including the airports of the region’s capital, Simferopol, and in Sevastopol, where Russia’s Black Sea fleet is headquartered.
Armed men are also controling vehicles on the main highway into the peninsula from mainland Ukraine, effectively cutting it off.
The pro-Russian authorities bring forward the date of their referendum to March 30.
The newly-chosen prime minister of Crimea, Sergiy Aksyonov, asks Russian President Vladimir Putin for help to ensure “peace and calm” on the peninsula.
In Moscow, Putin wins parliamentary approval to deploy troops in Ukraine
March 2
Pro-Kremlin forces lay siege to Ukrainian military facilities in Crimea and Ukraine’s navy chief Denis Berezovsky switches allegiance to the breakaway authorities of Crimea.
March 3
Ukranian border guards say troops are continuing to pour in to Crimea.
Moscow says deposed Ukrainian president Viktor Yanukovych is still the legitimate head of state, even if his authority is “negligible”.
March 5
Russian forces take partial control of two Ukrainian missile sites.
The Organization for Security and Co-operation in Europe (OSCE) says it is sending 35 military observers to Ukraine. The group will try unsuccessfully three times to get into Crimea.
March 6
The Crimean parliament tells Russian President Vladimir Putin they want the peninsula to become part of Russia.
They bring forward the date of the referendum again, to March 16, and say voters will be given the option of joining Russia or “signficant strengthening of their autonomy within Ukraine”.
Lawmakers also sanction the creation of the post of Crimean defence minister and announce that Ukrainian forces stationed in Crimea will be considered “occupying forces” and treated accordingly.
March 7
Russia’s parliament says it will respect the “historic choice” that Crimea makes in its referendum.
Moscow says OSCE observers barred from entry to Crimea did not get the required permission from the local authorities.
March 8
OSCE observers turn back again from Crimea, after shots are fired. No one is injured.
March 9
Russian President Vladimir Putin tells Western leaders the separatist government of Crimea is legitimate and “is taking actions based on international law and with the aim of guaranteeing the legitimate interests of the population of the peninsula”.
Russia offers an economic carrot, saying it will give $1.1 billion in aid to Crimea “to support the development of the industrial and economic infrastructure of Crimea”.
March 10
While Washington still refuses to recognise the weekend referendum, its ambassador to Kiev says the US would support greater autonomy for Crimea as long as this does not happen “under the barrel of a gun”.
March 11
German Chancellor Angela Merkel says Crimea has been “annexed”.
Lawmakers in Crimea vote for full independence from Ukraine. Russia’s foreign ministry says the declaration is “absolutely lawful.”
Pro-Moscow officials in Crimea launch a website for the referendum with a Russian domain name, while armed men take control of air traffic control in Simferopol, banning flights anywhere other than Moscow.
March 12
The G7 group of leading nations says the Crimean referendum will have “no legal effect” and threatens action if Moscow does not back down.
Ukrainian Prime Minister Arseniy Yatsenyuk meets US President Barack Obama at the White House.
MARCH 13
Washington warns Russia it is preparing a “very serious” response together with Europe to the Crimea vote.
Russia sends fighter jets to Belarus in response to a request by the country’s president, after NATO beefed up its presence in light of the crisis in Ukraine.
Ukraine’s parliament votes to create a new National Guard of 60,000 volunteers.
