(CNN) -- U.S. President Barack Obama has warned Russia that targeted sanctions are "ready to go," as the Geneva agreement to de-escalate the crisis falters. Officials have vowed more punitive international actions targeting Russia's economy if Moscow, in their view, continues to aggravate the situation. Key Putin allies, high-profile Russian oligarchs and possibly Russian institutions and companies, will be targeted, CNN has been told. Obama, at a news conference Friday in South Korea, said he would be talking to other European leaders about sanctions against Russia as the Ukraine crisis worsens. The West has already introduced sanctions, imposing financial and visa restrictions on around 30 Russian and Ukrainian officials -- but stopping short of measures that would hit trade.
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Russia risks being isolated by the West as it introduces visa bans and threatens more sanctions
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But the European Union is reliant on Russia for its energy supplies, and has strong trade links
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Trade is not so important between Russia and U.S., which is becoming energy self-sufficient
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These differences have impacted the economic approaches to Russia amid the crisis in Ukraine
Meanwhile, the West has offered $16 billion in aid for @placeholder, helping the country prop up its ailing finances.