The broader economic measures will hurt Moscow's ability to secure dollar financing for its banks, in the toughest attack yet on its economy since it became embroiled in the conflict in Ukraine.
"The major sanctions we're announcing today will continue to ratchet up the pressure on Russia, including the cronies and companies supporting Russia's illegal activities in the Ukraine," he said.
Obama denied the West was being drawn into a new Cold War with its former-Soviet foe, but warned that the United States and Europe are running out of patience Vladimir Putin's government.
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"Today in building on the measures we announced two weeks ago, the United States is imposing new sanctions in key sectors of the Russian economy -- energy, arms and finance," Obama said.
"We're blocking the exports of specific goods and technologies to the Russian energy sector," he said.
"We're expanding our sanctions to more Russian banks and defense companies. We're formally suspending credits and financing for economic development projects in Russia."
Earlier, the US Treasury had singled out VTB Bank, its subsidiary Bank of Moscow and Russian Agricultural Bank as three institutions joining the existing sanctions regime against Russia.
The sanctions ban any Americans or people in US jurisdictions from any new medium or long-term financing transactions with VTB Bank, its subsidiary Bank of Moscow and Russian Agricultural Bank.
All three are controlled by the Russian government.
The sanctions aim at choking off anything but short-term financing for the banks, which could inhibit their ability to build or maintain long-term lending business.
Under the rules, transacting in or providing financing for any new debt from the banks for more than 90 days is prohibited.
