SEVASTOPOL, Ukraine -- Ukrainian officials were tense Sunday, ordering up all military reservists to active duty while in the Crimean region in the south of the country, road traffic was blocked as telecommunications remained sporadic — two days after communication centers were seized by unknown armed men.
Russia's parliament unanimously voted to send troops into Ukraine Saturday, defiantly ignoring President Obama's warning to stay out.
Tension escalates in Ukraine CBS News
"The situation is very serious — the Russian army is blocking military bases of Ukraine in Crimea … They issued an ultimatum demanding that our soldiers disarm themselves or the bases will be stormed, said Ukraine's interim president and parliament speaker, Oleksandr Turchinov, on Sunday.
Speaking after a closed session of parliament in Kiev, Ukrainian Prime Minister Arseniy Yatsenyuk said his country "was on the brink of national disaster" and that if [Russian] President Putin wants to be the president who starts the war between two friendly and neighboring countries, he is inches away from doing it."
"This is not a threat, this is actually a declaration of war to my country," he added.
On Sunday, the interim government in Kiev said the military must be combat-ready as unidentified gunmen — thought to be Russian soldiers — were reported to be surrounding Ukrainian military and naval bases in Crimea, the strategic Black Sea peninsula.
"We need a unified army … we believe that discipline and coordination is now extremely important," said Andriy Paruby, secretary of Ukraine's security council, on Sunday.
The Associated Press reported that at least 13 trucks and four armored vehicles with mounted machine guns pulled up to the Perevalne military base in the Crimean peninsula. The trucks carried 30 soldiers each and had Russian license plates. Ukrainian troops stood on the other side of the gate, the AP reported.
Government buildings, airports and communications centers in Crimea continued to be held by groups of armed men, believed by some to be local defense militias backed by Russian military.
Local journalists reported that attempts to access the Crimea were unsuccessful after they were stopped and turned back at checkpoints manned by local defense groups, soldiers believed to be Russian and the paramilitary units from Kiev that were blamed for deaths of dozens of protesters last month.
Telecom operator Ukrtelecom said their lines had been damaged and that their technicians were "doing everything in their power to normalize the network operator and ensure a speedy recovery of the lines on the peninsula."
Anti-government activists entertain themselves next to a fire at a barricade in central Kiev, Ukraine, on Jan. 31.
NATO Secretary General Anders Fogh Rasmussen said in a statement Sunday that Russia's action in Crimea "violates the principles of the United Nations Charter. It threatens peace and security in Europe. Russia must stop its military activities and its threats."
Late Saturday, small rallies were held in Crimean cities expressing support for Russian help. Stories of hard-line Ukrainian nationalists from Kiev's Independence Square planning attacks on ethnic Russians have been circulating for weeks, and many people in this port city have either welcomed the Russian intervention or said they have no fear of Moscow's forces.
"This isn't really a crisis because all of Sevastopol was afraid of the Maidan movement," said 28-year-old waiter Konstantin Solovev. "We heard many stories that those people were threatening this city."
Even so, some locals created a petition signed by tens of thousands telling Russia they didn't need Russian help.
"Dear Mr. President of the Russian Federation, Vladimir Putin, We ethnic Russians and Russian-speaking Ukrainian nationals do not need other countries to defend our interests," the petition read. "We are grateful to you for support however would like to inform you that nobody has ever infringed our rights on Ukrainian territory ... therefore, we would ask you to not raise an internal question for our country which is not a burning issue for us ... Not to mention bringing troops in to regulate a conflict which you may see but which is not visible to us."
Tensions have been running high since Friday, when at least eight Russian transport planes landed at a military base, delivering unknown goods and personnel. Ukraine's Crimea province has an ethnic Russian majority and hosts the Russian navy's Black Sea fleet.
Most residents of the Black Sea peninsula have linguistic and cultural ties to Russia with a clear majority self-identifying as ethnic Russia.
Nowhere is that more apparent than in the port city of Sevastopol, home to the Russian navy's Black Sea fleet thanks to a lease agreement not set to expire until at least 2042.
The Russian tricolor flag flies over most buildings, and the Ukrainian language is rarely heard on the streets. In recent days pro-Russia rallies have drawn enthusiastic crowds that have reveled in the colorful display of nationalistic pageantry.
But already politicians in Moscow are proposing ways to annex Crimea. In Russia's Duma, lawmakers proposed legislation Friday that would ease the process of adding territory to the Russian Federation. Saturday, the upper house of the Russian parliament approved the use of force to protect Crimea.
Crimea has only been part of Ukraine since 1954, when it was ceded to Ukraine's Soviet republic when the whole region was part of the USSR.
A further wrinkle is the presence of Crimean Tartars — a Turkic people who have long inhabited the region who suffered enormously during Stalin's purges.
This minority has broadly supported the nationalist protesters in Kiev, and already scuffles have broken out between rival groups of Tartars and ethnic Russians. There are fears that Crimea's annexation would ignite ethnic conflict within the region itself.
At the same time, the interim government in Kiev — installed since Thursday and just a week after the ouster of ex-president Viktor Yanukovych — has been powerless to stop the events unfolding in the Crimea.
"Our soldiers (in Crimea) aren't falling for any provocations and are protecting Ukrainian military bases and warehouses," said Prime Minister Yatsenyuk. "Every half an hour Russian forces make provocations against our troops. Parliament has demanded that Russia stick to the Black Sea Fleet agreement and return the troops to their regular locations. I remind that any relocation of Black See Fleet troops must be approved by Ukraine, and Ukraine didn't give such permission."