SIMFEROPOL, Crimea — A power failure plunged much of the Crimean capital, Simferopol, into darkness Monday, the second partial blackout in two days, as the Ukrainian government in Kiev appeared to retaliate against Russia’s occupation and annexation of the peninsula by sharply cutting electricity supplied from the mainland.

Homes and businesses went dark across a large swath of the city, underscoring the vulnerability of the geographically isolated peninsula, which is dependent on mainland Ukraine for many vital services, including electricity and much of its water supply.

Officials here and in Moscow had anticipated such a move by the Ukrainian government.

In recent days, regional officials said they had acquired 900 generators to provide electricity to vital buildings, including hospitals. It was not immediately clear if those generators were in use.

In Moscow, Prime Minister Dmitry Medvedev said at a government meeting that Russian ministries should begin work in Crimea as soon as possible.

President Vladimir Putin has ordered officials to quickly begin work on a bridge to connect mainland Russia and the Crimean port city of Kerch, but the project will take years and cost between $3 billion and $5 billion.

Medvedev said that in the meantime, the issues of power and water supplies “should be settled through international negotiations,” according to the Interfax news service.

The blackout came as the acting president of Ukraine, Oleksandr Turchynov, formally ordered the withdrawal of the remaining Ukrainian military forces in Crimea, ending an increasingly futile effort by some troops to hold on to their bases after Russia’s annexation of the territory.

The Ukrainian military has been virtually powerless in the face of the incursion late last month by Russian special forces and other units.

In recent days, there has been a steady capitulation as Russian units seized base after base, in some cases firing in the air and using armored vehicles to smash through gates and walls.

Turchynov said the government had been instructed to find housing for the displaced troops and their families as well as for “all those who are currently forced to leave homes under pressure and aggression of the occupying troops of the Russian army.”

Over the weekend Russian forces stormed two of the last major installations in Crimea still under Ukrainian control — a base in Belbek adjacent to the Sevastopol airport on Saturday, and a naval base in Feodosia, on the peninsula’s eastern coast.

While some of the base seizures have been dramatic, they have generally been carried out without injuries.

In one case, at a technical and mapping installation near Simferopol, two men — a Ukrainian soldier and a member of a local pro-Russian self-defense militia — were shot and killed.

The circumstances of that incident remain murky, with local authorities saying that the men were killed by a sniper who was a member of a right-wing nationalist group from western Ukraine.

Turchynov’s announcement of a formal withdrawal was certain to speed the inevitable consolidation of Russian control over the Crimean Peninsula, which Putin said was being annexed to Russia in part to correct a historical mistake. The majority of the population here identify as ethnic Russians.

In 1954, Crimea was transferred from Russian control to the Ukrainian Soviet Socialist Republic in what Putin has described as a historical glitch. The occupation, however, was also a direct Russian response to the ouster of President Viktor Yanukovych, Ukraine’s former pro-Russian leader, after more than three months of civil unrest in Kiev, the capital.