Russian President Vladimir Putin has ordered his Defense Ministry to send Russian troops into eastern Ukraine's two breakaway regions, according to a decree published early on Tuesday, after he said Moscow would recognize their independence.
The Kremlin said Putin ordered the Russian forces to "maintain peace" in eastern Ukraine.
The decree did not specify when any such deployment would take place.
However, the move raises tensions, as Western leaders have warned Moscow could use a skirmish in the restive region as an excuse for a larger Russian attack.
Earlier Monday, Putin signed the decree stating Moscow now recognizes the "independence" of the self-proclaimed "Donetsk People's Republic" (DPR) and the "Luhansk People's Republic" (LPR).
Although the eastern Ukrainian provinces of Luhansk and Donetsk are claimed in whole by pro-Russia separatists, only parts of the provinces are under their control. Both provinces belong completely to Ukraine under international law.
It is not immediately clear if the order in the decree means Russian troops will be dispatched only within the territory already controlled by the separatists.
Following Russia's announcement, US Secretary of State Antony Blinken announced that US diplomatic staff in Ukraine would "spend the night in Poland," citing "security reasons." The staff had already been moved from Kyiv to the western city of Lviv.
Zelenskyy: Ukraine is 'not afraid'
Ukrainian President Volodymyr Zelenskyy delivered an address on Tuesday after urgent consultations with world leaders. He said he demanded "clear support" from the West.
Zelenskyy said that Ukraine is "not afraid of anything or anyone," after Russia's recognition of the two separatist regions.
He said that Ukraine's borders will remain as they are and that Russia's actions are "a violation of the sovereignty and territorial integrity" of Ukraine.
The Ukrainian leader accused Russia of legalizing its own troops, which he said have been in the Donbas since 2014.
He added that Ukraine supports a political and diplomatic settlement.
Ukrainian Foreign Minister Dmytro Kuleba said he would head to Washington to meet with US Secretary of State Blinken after they spoke about the developments.
"I underscored the need to impose tough sanctions on Russia in response to its illegal actions," he added.