The United States on Sunday said it will send its top diplomat to Kiev in a show of support and threatened economic sanctions against Russia but made clear it is not seriously considering military action over Ukraine.
The Obama administration sought to devise a diplomatic and economic strategy to reverse Russia's bloodless seizure of Ukraine's Crimea region and to dissuade Moscow from sending its forces further into the territory of its neighbour.
In a series of public statements and private conversations with reporters, however, US officials made it abundantly clear that their desire was to get Russian President Vladimir Putin to pull back without themselves getting into an armed confrontation.
"Right now, I think we are focused on political, diplomatic and economic options," a senior US official told reporters.
"Frankly our goal is to uphold the territorial integrity and sovereignty of Ukraine, not to have a military escalation," he added. "I don't think we're focused right now on the notion of some US military intervention. I don't think that necessarily would be a way to de-escalate the situation."
Read: Will go to the hilt to isolate Russia: John Kerry
US Secretary of State John Kerry will visit Kiev on Tuesday to show "strong support for Ukrainian sovereignty, independence, territorial integrity, and the right of the Ukrainian people to determine their own future, without outside interference or provocation," the State Department said in a statement.
Earlier, Kerry brandished the threat of economic sanctions on Russia, calling Moscow's moves on Ukraine an "incredible act of aggression" and saying that "all options are on the table," diplomatic code for the possibility of military action.
But, doing the rounds of Sunday morning television news shows to stress US disapproval of Russia's actions, Kerry emphasized Washington's desire for a peaceful resolution and analysts saw little chance of a US military response.
Ignoring warnings from President Barack Obama and other Western leaders, Putin won permission from his parliament on Saturday to use military force in Ukraine. The stated purpose was to protect Russian citizens in Ukraine following the ouster of the country's Russian-backed president a week ago.
Read: It's a David-and-Goliath battle for Ukraine and Russia
Putin got the green light from parliament after Russian forces had already gained control of Crimea, an isolated Black Sea peninsula with an ethnic Russian majority and where Moscow has long had a naval base.
"You just don't in the 21st century behave in 19th century fashion by invading another country on completely trumped-up pretext," Kerry told the CBS program "Face the Nation."
Kerry spoke of "very serious repercussions" for Moscow and said G8 nations and some other countries are "prepared to go to the hilt to isolate Russia" with an array of options available.
Kerry listed visa bans, asset freezes, trade isolation, and investment changes as possible steps, adding: "American businesses may well want to start thinking twice about whether they want to do business with a country that behaves like this."
Ukraine mobilized for war on Sunday after Putin asserted the right to invade Russia's neighbor. The crisis is the most significant showdown with the West since the end of the Cold War a quarter century ago.
'We're not there yet on US sanctions'
Analysts said US economic sanctions would likely have little impact on Russia unless they were accompanied by strong measures by major European nations, which have deeper trade ties with Moscow and are dependent on Russian gas.
"What the United States itself can do is relatively limited," said Steven Pifer, a former US ambassador to Ukraine who is now at Washington's Brookings Institution think tank. "The question is can you get the Europeans on board?"
US officials hinted at the possibility of imposing banking sanctions but it seemed unlikely that Washington would take such a drastic step against Moscow, whose cooperation it needs on issues such as the Iranian nuclear program.
"You're absolutely right that that's a vulnerability of Russian banks. We're looking at all of the options," said a second senior US official.
A third US official said economic sanctions would be imposed only if Russia continued to take "aggressive steps."
"It's not that there is an active plan at this moment about (imposing) sanctions on the Russians," said the third official, speaking on condition of anonymity. "There is a range of options we will consider if their behavior continues down this path."
Asked what those options were, the official replied: "we're not there yet."
Ejecting Russia from G8?
US officials also broadly hinted at the possibility of ejecting Russia from the so-called Group of Eight (G8) leading industrial nations club, with Kerry saying: "If Russia wants to be a G8 country, it needs to behave like a G8 country."
Obama, who on Friday evening publicly warned Putin there would be "costs" for any military intervention in Ukraine, on Sunday spoke to the leaders of Britain, Germany and Poland.
"(The primary point) in all of his calls has been to underscore the complete illegitimacy of Russia's intervention," in the Crimea region of Ukraine, the first US official told reporters in a conference call.
The US president also spent 90 minutes on the telephone with the Russian leader on Saturday. Kerry said Obama told Putin "that it was imperative to find a different path, to roll back this invasion and un-do this act of invasion."
Whether or not the US steps, which included cancelling planned meetings with Russian officials, would influence Moscow remained an open question and Obama faced criticism at home from Republican lawmakers who called his response so far weak.
"Every time the president goes on national television and threatens Putin or anyone like Putin, everybody's eyes roll, including mine. We have a weak and indecisive president that invites aggression," Senator Lindsey Graham, a frequent Obama critic, told the CNN program "State of the Union."