Secretary of State John Kerry said that "all options are on the table" when it comes to steps the U.S. can take to hold Russia accountable for its military movements in Ukraine, including economic sanctions and potentially military action.

In an interview with ABC's George Stephanopoulos today on "This Week," Kerry said Russian troops moving into the Ukrainian region of Crimea was "a military act of aggression" and that the U.S. will move swiftly to impose penalties if Russian President Vladimir Putin does not withdraw his troops.

While military force is among the options President Barack Obama is considering, Kerry said the U.S. and its allies hope they can avoid such action.

"The hope of the U.S. and everybody in the world is not to see this escalate into a military confrontation," he said.

More likely in the near term are economic sanctions on businesses and individuals - Kerry told Stephanopoulos that the U.S. is "absolutely" willing to impose such penalties, and that Congress should get to work on those sanctions along with a package of aid for Ukraine.

"We would call on Congress immediately, to the degree they are prepared to be helpful, that they immediately lay down with us an economic package in order to assist Ukraine," he said.

As he and the White House have warned over the past two days, Kerry also said there is a "distinct possibility" that the U.S. will boycott the Group of Eight summit, scheduled to be held in June in Sochi, Russia - the site of the Winter Olympics - and encourage other G8 member countries to do the same.

Kerry said Russia's invasion of Crimea will have an effect on its standing among the rest of the world's largest economies.

"It's a 19 th century act in the 21 st century and it really puts at question Russia's capacity to be within the G8."