Ukraine's acting president said the commander of the country's navy has been freed after being held by Russian forces and Crimean authorities at the navy's headquarters in Crimea.
A statement by President Oleksandr Turchynov Thursday said Rear Admiral Sergei Haiduk was released along with an unspecified number of civilian hostages.
The group was detained after the Ukrainian naval base in the Crimean port of Sevastopol was seized Wednesday. Reports indicated pro-Russian militiamen -- Crimea's so-called "self-defense" forces -- were behind the takeover, but President Turchynov's statement suggests Russian forces were also involved.
The seizure, which faced no resistance from Ukrainian service personnel, came one day after Moscow signed a treaty with local authorities making Crimea part of Russia. The region voted to break away from Ukraine and join Russia in a referendum Sunday that the U.S. and European Union have declared illegal.
On Wednesday, Ukraine's security chief said the country has drawn up plans to evacuate its outnumbered military personnel from the Crimean peninsula, effectively surrendering military control of the region.
In announcing the withdrawal, Andriy Parubiy -- secretary of Ukraine's National Security and Defense Council -- said Kyiv will seek United Nations support in turning the peninsula into a demilitarized zone. He also said Ukraine is planning to hold military maneuvers "with our allies," but did not elaborate.
Meanwhile, in a continuation of diplomatic efforts to end the crisis, United Nations Secretary-General Ban Ki-moon was meeting Russian President Vladimir Putin and Russian Foreign Minister Sergei Lavrov in Moscow Thursday. On Friday, he will meet in Kyiv with Ukrainian President Turchynov and Prime Minister Arseniy Yatsenyuk.
Ukraine's deputy prime minister and defense minister traveled Wednesday from Kyiv to Crimea in an attempt to defuse tensions, but were denied entry into the territory. International observers have also been repeatedly turned away from the peninsula.
U.S. Vice President Joe Biden told reporters in Vilnius, Lithuania on Wednesday that Russia will face "increasing political and economic isolation" as long as it continues on what he called "its dark path."
However, Putin maintained that the Crimean peninsula has always been an "inalienable" part of Russia.