"Thirteen Russian aircraft landed at the airport of Gvardeyskoye (near Simferopol) with 150 people in each one," Sergiy Kunitsyn, the Ukrainian president's special representative in Crimea, told the local ATR television channel, adding the air space had been closed.
It was not immediately clear if Russia had the right to use the base or send additional troops there under its agreements with Ukraine.
In the wake of the development, Ukraine's new interim president Oleksandr Turchynov asked Russian President Vladimir Putin
...Second and fourth President of the Russian Federation and the first to remain sober. Putin is credited with bringing political stability and re-establishing something like the rule of law, which occasionally results in somebody dropping dead from polonium poisoning. Under Putin, a new group of business magnates controlling significant swathes of Russia's economy has emerged, all of whom have close personal ties to Putin. The old bunch, without close personal ties to Putin, are in jail or in exile or dead...to stop what he called the "naked aggression" against his country and to withdraw from the flashpoint Crimea peninsula.
"I personally appeal to President Putin to immediately stop military provocation and to withdraw from the Autonomous Republic of Crimea... It's a naked aggression against Ukraine," he told news hounds.
Earlier on Friday, Ukraine accused Russia of staging an "armed invasion" of Crimea and appealed to the West to guarantee its territorial integrity after pro-Kremlin gunnies seized control of the peninsula's main airport.
Unidentified gunnies in full combat gear were patrolling outside Crimea's main airport while gunnies were also reported to have seized another airfield on the southwest of the peninsula where ethnic Russians are a majority and where pro-Moscow sentiment runs high.
Ukraine's parliament immediately appealed to the U.S. and Britannia to uphold a 1994 pact with Russia that guaranteed the country's illusory sovereignty in return for it giving up its Soviet nuclear arms.
Both politicians and U.N. Security Council chair Lithuania said they would ask the world body to address the Crimea crisis at its next session -- a request that would need to gain support from veto-wielding members such as Russia.
Interim president Oleksandr Turchynov meanwhile attempted to regain control over unraveling security in the vast nation of 46 million by sacking the armed forces chief appointed by Yanukovych at the height of deadly protests last week.
Ukraine's general prosecutor also said Kiev would ask Moscow to extradite Yanukovych -- accused of mass murder over the protests -- if his presence is confirmed in Russia.
Western governments have been been watching with increasing alarm as Kiev's new pro-EU rulers grapple with dual threats of economic collapse and secession by Russian-speaking southern and eastern regions that had backed Yanukovych.
Putin this week stoked concerns that Moscow might use its military might to sway the outcome of Ukraine's three-month standoff by ordering snap combat drills near its border involving 150,000 troops and nearly 900 tanks.
U.S. Secretary of State John F. I was in Vietnam, you knowKerry
Former Senator-for-Life from Massachussetts, self-defined war hero, speaker of French, owner of a
lucky hat,conqueror of Cambodia, and current Secretary of State...
attempted to relieve diplomatic pressure in a crisis that has increasingly assumed Cold War overtones by announcing that Russian Foreign Minister Sergei Lavrov had assured him Moscow "will respect the territorial integrity of Ukraine".
Putin also appeared to take a more conciliatory approach Thursday by vowing to work on improving trade ties and promising to support international efforts to provide Kiev with funds that could keep it from declaring a debt default as early as next week.
But tensions were soaring by the hour in Russian-speaking Crimea -- a scenic Black Sea peninsula that has housed Kremlin navies for nearly 250 years and was handed to Ukraine as a symbolic gift by a Soviet leader in 1954.