By Mick Krever, CNN
(CNN) - If diplomacy fails to persuade Russia to withdraw its forces from the Ukrainian region of Crimea, the world should apply the "strongest means" on Russia, former Ukrainian Prime Minister Yulia Tymoshenko told CNN's Christiane Amanpour in an exclusive interview Monday.
Amanpour asked Tymoshenko if she was calling for the West to use military force against Russia.
She would not directly answer the question, saying that she "cannot solve this issue," but she issued an appeal to help Ukraine.
"I am asking all the world, personally every world leader, to use all the possibilities in order to avoid Ukraine losing Crimea."
Russia has complete "operational control" over Crimea, a senior U.S. official has told CNN.
This was Tymoshenko's first international interview since her release from prison just over a week ago, following a truce between then-President Viktor Yanukovych and the opposition. She spent
the last years behind bars on what the West called politically motivated charges.
Ukraine is just "one step" away from war, Tymoshenko said.
The Russian Duma, or parliament, has started debate on "the draft of the law of annexation of Crimea from Ukraine," she told Amanpour.
The Duma website confirms that a draft law has been put forward on defining the process whereby a country or territory can seek to be annexed by Russia.
If "Ukraine is left on its own and is given to Russia," Tymoshenko said from Kiev, "then the world will change."
"Not only politics and life in Ukraine will change - the politics and life will change practically everywhere in the world."
She called on the world's superpowers to bring a solution to the crisis.
Russia issued an ultimatum to Ukrainian forces in Crimea to clear out by Tuesday morning or face a "military storm," Ukrainian officials said Monday. But a spokesman for the Russian Black Sea Fleet said there are no plans to storm Ukrainian military units in Crimea, according to the Interfax news agency.
Earlier, Russia rejected accusations that it was acting aggressively toward Ukraine.
"We call for a responsible approach, to put aside geopolitical calculations, and above all to put the interests of the Ukrainian people first," Russian Foreign Minister Sergey Lavrov said at a U.N. human rights meeting in Geneva, Switzerland.
Ukraine's new interim government has mobilized troops and called up military reservists, but Tymoshenko said her country did not want a repeat of Russia's 2008 war with the country of Georgia over the separatist territories of South Ossetia and Abkhazia.
"We are perfectly aware of the balance of forces between Russia and Ukraine," she said. "We cannot put people to death."
Russia's military dwarfs Ukraine's - with 845,000 total troops in 2012 versus Ukraine's 130,000 - and Russia spends nearly 50 times as much on its military.
"Every response to Russian aggression will be used by the aggressor just to destroy Ukraine," Tymoshenko said.
She said Russia was issuing an ultimatum to Ukraine to reinstall the former, Russia-sympathetic President Yanukovych in order to stop the aggression.
She said that the return of the "corrupted" and "blood-stained" leader was "not acceptable."
"All Ukraine is against it," she said. "All Ukraine will not support it."
Even those in eastern Ukraine, she told Amanpour, are against the aggression.
"Both east, west - they're united. They don't want war. They want stability and peace, and they're against the aggression."
Amanpour asked Tymoshenko, arguably the most powerful politician in Ukraine right now, whether she plans to once again run in an election to lead her country.
"Every day, every minute, we live with one thing: We're losing Ukraine. Nobody is talking politics here. Nobody talks about elections here."