(CNN) — The Obama administration said Sunday that action against Russia for its incursion into Crimea is working, as Moscow's economy struggles under sanctions imposed by the United States and other countries.
"This is exactly already a real cost for (Russian President Vladimir) Putin and in Russia and the economy," White House deputy national security adviser Tony Blinken said on CNN's "State of the Union."
"The stock market went down significantly including this week. We saw the ruble get an all-time low. Investors who are looking at Russia (are) sitting on the fence because they are looking for three things: They are looking for stability. They are looking to see if the country makes good on integrated agreements, and if it is working with the world economy. All three areas, Putin has such tremendous doubt."
But as Russian forces continued consolidating their control of Crimea over the weekend, a top Ukrainian official said chances are "growing" for a full-blown war between his country and Russia.
Amid a buildup of Russian forces on Ukraine's eastern border, Andrii Deshchytsia, Ukrainian acting foreign affairs minister, said his country is "ready to respond" as the situation becomes "even more explosive" than it was last week.
"The Ukrainian government is trying to use all their peaceful means and diplomatic means to stop Russia. But the people are also ready to defend their homeland," he said on ABC's "This Week."
Blinken said the large-scale drills by Russia near the Ukrainian border could be an act of intimidation, but it's also possible Russia plans to move forces in.
Former Secretary of State Madeline Albright told CNN's Candy Crowley that Putin "is basically trying to threaten and show that he has power."
"I think it's very worrisome," she said, adding that economic sanctions against Russia will "take a while to bite" but have already had major effects.
Blinken said the White House is looking at military assistance, though it's "unlikely to prevent an invasion" of Ukraine.
Russia's movement to the Ukrainian border comes as President Barack Obama prepares to head overseas on a four-day European tour, where he'll try to appeal to European leaders for a tougher response to Putin's movement into Crimea.
Albright said Obama's travels "will give an opportunity to the President and the European allies and other allies to make what I think is a pretty clear message even clearer."
Citizens in the disputed peninsula of Crimea voted to leave Ukraine in a hastily arranged referendum earlier this month. Russia swiftly recognized the succession.
The United States announced its own new round of sanctions last week against 20 individuals and a bank. Washington had already announced sanctions on 11 individuals. EU leaders also imposed a new round of sanctions against 12 individuals last week, bringing the total number of people facing EU asset freezes and travel bans to 33.
So far, European powers such as Germany and Britain have been unwilling to embrace significant economic sanctions against Russia because of their strong trade and investment ties with Moscow.
Rep. Mike Rogers, a Republican from Michigan and Intelligence Committee chairman, said Putin's takeover of Crimea isn't his last attempt to exert more control in the region.
"It certainly appears by everything that Ukrainian intelligence officials believe, certainly U.S. intelligence officials believe, that Putin is not done in Ukraine," he said on NBC's "Meet the Press."
"We need to be a little bit tougher with this, with Putin, or he is going to continue to take territory to fulfill what he believes is rightfully Russia."
Meanwhile, a Ukraine financial aid package is stalled in Congress, caught up in a fight over IMF funding and an unrelated dispute over rules aimed at curbing political activities by nonprofit groups. The Senate will again take up the bill next week. The package includes $1 billion in U.S. loan guarantees as well as $50 million to boost democracy building in Ukraine and $100 million for enhanced security cooperation for Ukraine and some of its neighbors.
In interviews with CBS on Sunday, Sens. Dick Durbin and Kelly Ayotte backed military aid to Ukraine.
"We've got to strengthen them and help them with advice and backing," said Durbin, the No. 2 Democrat in the Senate.
Taking it one step further, Ayotte, a Republican from New Hampshire, said the U.S. should broaden sanctions on Russia's economy to the country's entire financial sector.
Mitt Romney, the GOP's presidential nominee in 2012, said the President should have been more forceful with Putin from the start.
"I'm saying what (Obama) should have done from the very beginning was have the judgment to understand that Russia was not our friend, that Russia had very different ambitions and interests, that you have to stand strong," he said.
Romney, who called Russia the United States' "No. 1 geopolitical foe" during a debate, said Obama's "faulty judgment" led to the current diplomatic challenges with the country.