Russian troops have entered several Ukrainian military installations, asking some soldiers to leave, while making sure that others can't escape.

These extremely provocative acts may be designed to force the Ukrainians to fire the first shot, thus giving the Russians an excuse to invade the Russian-speaking eastern provinces, in addition to annexing the Crimea.

Reuters:

Pressure levels have increased markedly in the two days since the region's pro-Moscow leadership declared that it is now part of Russia and announced a March 16 referendum to confirm it.

President Vladimir Putin declared a week ago that Russia has the right to invade Ukraine to protect Russian citizens, and his parliament has voted to change the law to make it easier to annex territory.

So far, Russia's seizure of the Black Sea peninsula has remained bloodless, but its forces have become increasingly aggressive towards Ukrainian troops, who are trapped in bases and have offered no resistance.

Russian troops drove a truck into a missile defense post in Sevastopol, the home of both their Black Sea Fleet and the Ukrainian navy, and took control of it overnight. A Reuters reporting team at the scene said no-one was hurt.

Ukraine's border service said Russian troops had also seized a border guard outpost in the east of the peninsula overnight, kicking the Ukrainian officers and their families out of their apartments in the middle of the night.

"The situation is changed. Tensions are much higher now. You have to go. You can't film here," said a Russian soldier carrying a heavy machine gun, his face covered except for his eyes, at a Ukrainian navy base in Novozernoye.

Polish Foreign Minister Radoslaw Sikorski said on Saturday Poland had evacuated its consulate in Sevastopol due to "continuing disturbances by Russian forces".

About 100 armed Russians are keeping watch over the Ukrainians at the base, where a Russian ship has been scuttled at the entrance to keep the Ukrainians from sailing out.

"Things are difficult and the atmosphere has got worse. The Russians threaten us when we go and get food supplies and point their guns at us," said Vadim Filipenko, the Ukrainian deputy commander at the base.

The Crimea annexation referendum is scheduled for March 16 where it is expected to pass by an overwhelming margin. The Russian parliament has indicated it will be easily approved.

But what about the rest of Ukraine? Putin is being watchful as the west's response to his aggression plays out. He will be prepared to invade the eastern and southern provinces of Ukriane if the opportunity presents itself and he can do it without much cost. So far, the weak, disorganized response by the west must be satisfying to Putin, but escalating the crisis carries with it unknowns that he may think present too much of a risk. He can afford to be patient. Ukraine is far from being out of the woods as its economy is near meltdown and the restive eastern provinces may try to break away anyway.

The president, on vacation in Key Largo, has had nothing to say about Ukraine since Thursday.