U.S. President Barack Obama said Thursday that a planned referendum on Crimea's future violates the both the Ukrainian constitution and international law, the Anadolu agency reported.
The semi-autonomous Crimean parliament voted unanimously Thursday to join Russia, and called for a referendum on the region's future with Ukraine on March 16. Its decision comes as Russian armed forces continue to maintain their presence on the peninsula.
Speaking at the White House, Obama said: "The proposed referendum on the future of Crimea would violate the Ukrainian constitution and violate international law."
"Any discussion about the future of Ukraine must include the legitimate government of Ukraine."
"If this violation of international law continues, the resolve of the United States and our allies and the international community will remain firm," said Obama.
Russia has said that it is acting to protect ethnic Russians and Russian nationals in Crimea; Obama re-stated his support for international monitors to be sent to the region to address the Kremlin's concerns.
Commenting on new visa bans and plans for sanctions announced by the United States earlier today, Obama said that the actions had been taken in consultation with Washington's European allies, and they "continue our efforts to impose a cost on Russia and those responsible for the situation in Crimea".