Former Republican presidential candidate Mitt Romney said Sunday that President Barack Obama has been naive about Russia's "intentions and objectives," and that the president's "faulty judgment" on Russian President Vladimir Putin has made the current situation in Ukraine worse.

"The president's naivete with regards to Russia and his faulty judgment about Russia's intentions and objectives has led to a number of foreign policy challenges that we are facing," Romney told Bob Schieffer on CBS's "Face the Nation." "Unfortunately, not having anticipated Russia's intentions, the president wasn't able to shape the kind of events that may have been able to prevent the kinds of circumstances that you're seeing in the Ukraine."

Putin formally annexed Ukraine's Crimean peninsula, where a majority of the population is Russian, on Friday. Russian forces have seized Ukraine's military bases in the area. The annexation has led to the worst crisis in the region since the end of the Cold War, and brought U.S.-Russian relations to a new low.

The escalation has served as an unfortunate vindication for Romney, who was mocked by Obama during the 2012 presidential race for saying that Russia was the greatest geopolitical foe facing the United States.

"[W]hen you were asked what's the biggest geopolitical threat facing America, you said Russia, not al Qaeda," Obama said during a debate. "In the 1980s, they're now calling to ask for their foreign policy back because, you know, the Cold War's been over for 20 years."

Romney insisted Sunday that the crisis in Ukraine could have been predicted, and he faulted the president for not moving earlier to avert it. Pressed by Schieffer on what Obama could have done, Romney said the U.S. could have taken steps earlier to plan sanctions against Russia in concert with other countries.

"There may have been some people surprised, but there have been many, many others that predicted Russia would try to grab other territories. This had been prepared for some time and we could have taken action earlier on," Romney said. "We would have had far more options to shape events to keep Russia from moving in -- for instance, working with our allies around the world to develop sanctions and communicate those to Russia very, very clearly."

"We really need to understand that Russia has very different interests from ours. This is not fantasyland," Romney added. "This is a reality where they are a geopolitical adversary."

Sen. Dick Durbin (D-Ill.) told Schieffer that Romney was mistaken if he thought earlier planning on sanctions could have prevented the crisis.