(CNN) -- President Barack Obama wrapped up a European trip dominated by Russia's annexation of Crimea by shifting the focus of the U.S. and allied response to helping Ukraine rather than confronting Moscow. "I've been very clear in saying that we are going to do everything we can to support Ukraine and the Ukrainian people," Obama said Thursday at his final European news conference of the trip, this time in Rome with Italian Prime Minister Matteo Renzi. "But I think it's also important for us not to promise and then not to be able to deliver." While Obama pledged tougher sanctions on Russia if President Vladimir Putin continued his expansionist ways, he emphasized steps that don't involve the Russians -- such as Thursday's announcement that the International Monetary Fund would lend Ukraine up to $18 billion.
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NEW: President Obama, European leaders pledge unity against Russian expansion
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NEW: Obama says stronger sanctions on Russia will impact U.S. companies
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NEW: NATO allies have to spend more on defense, Obama says
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NEW: Italy's Prime Minister pledges support for NATO response to Russia
Obama acknowledged Thursday that expanding sanctions to target Russia's financial services, energy, mining, defense and engineering industries would impact U.S. and @placeholder companies that do business with Russia in the connected global economy.