Kiev, Ukraine: Ukraine is ready to fight for its sovereignty, Prime Minister Arseniy Yatsenyuk declared in Kiev, after pro-Russian forces seized control of the Black Sea region of Crimea, triggering one of the biggest crises in Russia's relations with the West since the end of the Cold War.
Ukraine told Russia that a military invasion would be an act of war following a vote by lawmakers in Moscow to give President Vladimir Putin the right to send troops into the neighbouring country. The Ukrainian government, which put its military on full combat alert, is taking "all measures" to ensure peace and unity, Mr Yatsenyuk said.
On Sunday, Ukraine announced it would call up all military reservists as witnesses said a group of Russian soldiers had blocked about 400 Ukrainian marines at their base in the eastern Crimean port city of Feodosiya and were calling on them to surrender.
The head of the National Security and Defence Council Andriy Parubiy told reporters that the council had ordered the Defence Ministry to "call on all those that armed forces need at the moment across Ukraine," adding that the mobilisation was to "ensure the security and territorial integrity of Ukraine".
"The Ukrainian state will protect all citizens no matter in which region they live in and which language they speak or which church they attend," acting Ukrainian President Oleksandr Turchynov said.
Ukraine's defence chief said earlier Russia had already sent 30 armoured personnel carriers and 6000 additional troops into Crimea to help pro-Kremlin militia gain broader independence from the new pro-EU leaders in Kiev.
Foreign Minister Andriy Deshchytsya also appealed to NATO "with a request to consider all options to defend the territorial integrity and sovereignty of Ukraine".
The North Atlantic Treaty Organisation called emergency talks with its 28 ambassadors for Sunday.
British Foreign Secretary William Hague was due in Kiev later Sunday for talks with Mr Turchynov.
Ukraine is facing off against Mr Putin, who is trying to assert his power over parts of Ukraine with large ethnic Russian populations after last week's overthrow of President Viktor Yanukovych. The military movements risk destabilising the country as its new government looks to the US and Europe for a bailout to avoid default. Russian president Vladimir Putin told US President Barack Obama that Russia may act in Ukraine if violence spreads to Russian-speaking regions, the Kremlin said in a statement.
Speaking live on Ukrainian TV, acting Mr Turchynov said he had also ordered stepped up security at nuclear power plants, airports and other strategic infrastructure.
"This is probably the most dangerous situation in Europe since the Soviet invasion of Czechoslovakia in 1968," said a Western official on condition of anonymity.
Tensions in the mostly Russian-speaking Crimea are worsening after gunmen took control of the regional legislature this week and installed a pro-Kremlin premier, Sergey Aksenov.
Heeding a request by Mr Putin to protect ethnic Russians, lawmakers in Moscow voted unanimously on Saturday to allow him to send troops to its neighbour after unidentified troops seized facilities in Ukraine's southern Crimea region.
Russian forces solidified their control of Crimea and unrest spread to other parts of Ukraine on Saturday. Pro-Russian demonstrators clashed, sometimes violently, with supporters of Ukraine's new authorities and raised the Russian flag over government buildings in several cities.
Crimea was given to Ukraine by Russia in 1954 by then- Soviet leader Nikita Khrushchev. Ethnic Russians comprise 59 percent of Crimea's population of about 2 million people, with 24 percent Ukrainian and 12 percent Tatar, according to 2001 census data. Russians make up 17 percent of Ukraine's entire population of 45 million people.
Ukraine is diverting funds for the military, Mr Yatsenyuk said. Mr Putin had no reason to request the use of force against Ukraine as Russians aren't under threat in the country shaken by an uprising, Mr Turchynov said. Earlier he accused Russia of "naked aggression." Ukraine's defence minister said on Saturday that Russia has sent 6000 more soldiers into Crimea in the past 24 hours, while Crimean Premier Sergey Aksenov, who asked Russia for help, said Russian troops were guarding key buildings there, Interfax news service reported.
The extent of Russia's growing estrangement from the West was underscored when the US, the UK and Canada announced they were suspending preparations for a G8 summit that was due to be held in June in Sochi – which hosted the Winter Olympics last month.
While speaking on NBC’s Meet the Press, US Secretary of State John Kerry has bluntly warned Russia that it also risks losing its place among the G8 nations over the escalating situation in Crimea.
The latest moves followed days of scripted, bloodless turmoil on the peninsula, the scene of centuries of wars and seen by Moscow as a crown jewel of the Russian and Soviet empires. What began on Thursday with the early-morning takeover of the regional parliament building by mysterious troops continued Saturday afternoon as dozens of those soldiers - almost certainly Russian - moved into the streets around the parliamentary complex and seized control of regional airports, amid street protests by pro-Russian Crimeans calling for Moscow's protection from the new government in Kiev.
That government came to power last week in the wake of months of pro-democracy protests against the now-fugitive president, Viktor Yanukovych, and his decision to turn Ukraine toward Russia, its longtime patron, instead of the European Union. Despite the calls for Moscow's help, there has been no sign of ethnic Russians facing attacks in Crimea or elsewhere in Ukraine.
Putin's goal may instead be to ensure Russia's military dominance of the region survives through its hold on the deep- water Black Sea port of Sevastopol, which it received in a leasing deal with Ukraine until 2042. The threat of military force may set the stage for a referendum slated for March 30 in Crimea over whether the country should have more independence from Kiev, said Ruslan Pukhov, director of the Moscow-based Center of Analysis of Strategies and Technologies.
Bloomberg, AFP, AP, Reuters