The United States warned Moscow it was on a "dark path" to isolation on Wednesday as Russian troops seized two Ukrainian naval bases, including a headquarters in the Crimean port of Sevastopol where they raised their flag, according to the Associated Press.

The seizure came as Russia and the West dug in for a long confrontation over Moscow's annexation of Crimea, with the United States and Europe groping for ways to increase pressure on a defiant Russian President Vladimir Putin, the AP reported.

"As long as Russia continues on this dark path, they will face increasing political and economic isolation," said U.S. Vice President Joe Biden, according to the AP. Biden was in the Lithuanian capital Vilnius, part of a quick trip to reassure Baltic allies worried about what an emboldened Russia might mean for their nations.

United Nations chief Ban Ki-moon meets Putin in Moscow on Thursday and travels to Kiev on Friday, the AP reported. He will urge a peaceful end to a crisis that began when Ukraine's president abandoned a trade pact with the European Union and turned instead to Moscow, prompting violent street protests that led to his overthrow.

Russian lawmakers raced to ratify a treaty making Crimea part of Russia by the end of the week, despite threats of further sanctions from Washington and Brussels, the AP reported. The Russian military then moved swiftly to neutralize any threat of armed resistance in Crimea.

Ukrainian military spokesman Vladislav Seleznyov said the commander of the Ukrainian navy, Admiral Serhiy Haiduk, was driven away by what appeared to be Russian special forces, according to the AP. Russian troops seized another Ukrainian naval facility in Crimea late on Wednesday.

In Washington, the White House condemned Russian moves to seize Ukrainian military installations, saying they are creating a dangerous situation, the AP reported. NATO accused Russia of trying to "redraw the map of Europe".