Ukraine's security council ordered Sunday the Defense Ministry to launch a full military mobilisation in response to Russia sending more troops to Crimea.
Ukraine's new government decided to call up military reservists amid concerns of an expanded Russian invasion into the Crimea Peninsula.
Ukraine's armed forces are said to comprise a total of 130 000 troops and reserves of one million.
Ukraine put its military on full combat alert on Saturday. The government ordered enhanced security measures at nuclear power plants and other strategic sites.
On Sunday, Ukraine's parliament called for international monitors to help ensure the safety of its nuclear power plants amid the escalating tensions with Russia.
On Saturday, Russia's upper house of parliament approved a request of President Putin to use the country's military in Ukraine.