Russia has reported taking control of all Ukrainian military facilities in Crimea and announced plans to boost its own military presence on the strategically placed peninsula.
All 193 military garrisons of the Ukrainian armed forces in Crimea have raised Russian flags, Army General Valery Gerasimov, Chief of the Russian General Staff, told reporters on Wednesday.
The takeover of Ukrainian facilities had been largely peaceful, with the exception of a shootout at one base in which a Ukrainian serviceman and a Crimean activist died.
The Russian military chief said about 1.500 Ukrainian military personnel out of about 18,000 had chosen to return to Ukraine and would be repatriated by train.
The Ukrainian Defence Ministry confirmed on Wednesday that the first 131 marines had left Crimea. It said 4,300 Ukrainian servicemen had asked to return to Ukraine.
Russia plans to substantially beef up its forces in Crimea, a defence official said on Wednesday.
The unnamed official told the Interfax news agency that Russia would deploy Topolev Tu-22M3 strategic bombers on the peninsula by 2016. The long-range bombers had been based in Crimea before the breakup of the Soviet Union in 1991.
"The need for these aircraft in the south was always there and now is the right time to return them", the defence official said.
The plan further calls for deploying new submarines, air-superiority and marine patrol aircraft in Crimea. A helicopter carrier will be deployed in the region in 2017.
U.S. President Barack Obama, for his part, has called for boosting NATO defences to deter expansionist Russia.
Mr Obama told European leaders in Brussels that he was concerned about declining defence budgets among some NATO members and that they must be ready to pay more for their defences.
"If we have collective defence, it means everyone’s got to chip in", Mr Obama said after meeting with the leaders of the European Union.
"Our freedom isn’t free, and we have to be able to pay for the assets, the personnel, and the training to make sure we have a credible NATO force and an effective deterrent force,» the U.S. leader said. Everyone is going to have to make sure they are engaged and involved, and I think that will help build more confidence among member states".