Ukraine’s parliament has voted to create a 60,000-strong National Guard to bolster the country’s defences.
The vote came ahead of Sunday’s referendum in Crimea, now controlled by pro-Russian forces, on whether citizens want to join Russia.
President Vladimir Putin insists Russia is not to blame for the crisis.
But Germany’s Angela Merkel says Moscow faces “massive” political and economic damage if it refuses to change course. The US has also threatened action.
Russia was exploiting the weakness of neighbouring Ukraine, rather than acting as a partner for stability, the German chancellor said on Thursday, adding that there was no military solution to the crisis.
The Russian military and pro-Russian armed men moved in to seize key sites in Crimea – an autonomous region of Ukraine whose population is mainly ethnic Russian – in late February after the fall of President Viktor Yanukovych.
But Putin told Paralympic delegates in the Black Sea port of Sochi on Thursday: “Russia was not the initiator of the circumstances that have taken shape.”
The German chancellor has threatened an escalating series of EU measures if Russia does not relax the tension in Ukraine.
In a statement to the Bundestag, she said political and diplomatic measures, rather than military action, were the way to resolve the crisis.
“If Russia continues on its course of the past weeks, it will not only be a catastrophe for Ukraine,” she said.