President Obama, insisting the U.S. would preserve an ironclad commitment to its European partners, said Wednesday that Russia “stands alone” in the wake of annexing Crimea.

Appearing at a joint press conference in Brussels, Belgium, with European leaders, Obama defended his administration's approach to deterring Russian President Vladimir Putin from making additional incursions into Ukraine.

“If Russia stays on its current course, the consequences for the Russian economy will continue to grow,” Obama said, touting the “most significant sanctions Russia has faced since the end of the Cold War.”

However, Obama will leave Europe this week without any additional punishments for the Russian annexation of Crimea, just the threat of future sanctions if Putin gets more aggressive in Ukraine.

Critics have accused the president of not doing enough to send a clear signal to Putin and appearing disinterested in the Russian leader’s motivations.

Obama said earlier this week that he was more concerned with finding a solution to the Crimean crisis than playing armchair psychologist on Putin.

And he promised that future sanctions — potentially on the Russian energy, banking and arms sectors — would sting if Putin ignored U.S. warnings.

Some have expressed concerns that slapping Russia with such sanctions could potentially harm the economies of European nations, a major Russian trade partner.

Obama acknowledged that reality Wednesday, saying he was “mindful” those penalties would “have some impact on the global economy.”