Russian forces began moving troops into Ukraine's Crimea region by ferry on Monday after seizing control of the border post on the Ukrainian side of the waterway, Ukraine's border guards said.
Russians who seized the isolated Black Sea peninsula have been surrounding the ferry terminal for days but until now had not taken control of Ukraine's border guard station.
A border guard spokesman said Russian troops seized the checkpoint after the border guards tried to stop two buses carrying seven armed men, and the next ferry brought three truckloads of soldiers across.
And Kiev's U.N. Ambassador Yuriy Sergeyev said on Monday that Russia has deployed roughly 16,000 troops to the Crimea region since last week,
"Beginning from 24 February, approximately 16,000 Russian troops have been deployed in Crimea by the military ships, helicopters, cargo airplanes from the neighboring territory of the Russian Federation," Sergeyev told an emergency meeting of the U.N. Security Council on the crisis in his country.
Earlier on Monday, the Ukrainian border guards said they had seen Russia assembling an armored column on its side of the 2.7 mile wide Kerch strait that separates the Crimea peninsula from southern Russia.