KIEV, Aug. 24 - President Petro Poroshenko, in an interview with CNN on Wednesday, said that Russian President Vladimir Putin wants "the whole Ukraine" to be part of the "Russian Empire."

"It is absolutely the same situation like Russian bombardment in Aleppo," he told CNN's Christiane Amanpour in the interview.

"They have only one purpose -- [the] world should be less stable, less secured," Poroshenko said.

Had you asked him in 2013, Poroshenko said, if it would have been possible for Russia to "occupy the Crimea," he would have said "no, this is not possible -- there is some red line, and Putin [will] not cross this line."

"If you asked me in January, year 2014," he went on, if it was possible that "thousands of Russian regular troops will penetrate on Ukrainian territory in the east of my country in July and August," I would have said, "no, this is not possible."

With those moves, he said, the world "is completely changed."

"Russian aggression completely destroyed the post-war global security system," he said.

Twenty-five years after independence, he said, the fight goes on -- "fighting for freedom, fighting for democracy, fighting for sovereignty and territorial integrity."

Ukraine has become a somewhat surprisingly prominent issue in the American election.

That's due in part to Donald Trump's former campaign chairman, Paul Manafort, who has served as an adviser to former Ukrainian President Viktor Yanukovych, who fled office in 2014 after massive protests in the country.

It was recently announced that Ukraine's anti-corruption bureau is investigating Manafort and whether he received millions in potentially illegal cash payments from the country's former ruling party.

Poroshenko would not comment on the specifics of the case, but pledged that any possible charges -- against Manafort or anyone else -- would only come after a "transparent and independent investigation."

U.S. Republican Presidential Candidate Donald Trump has stirred controversy with his statements on Russia. The Republican presidential nominee has been criticized for his comments expressing openness to recognizing Russia's annexation of Crimea, and has called on the Russian government to share emails it possibly hacked from Democratic nominee Hillary Clinton and drawn rebukes from critics who say he's soft on a traditional US adversary.

"I have no doubt that we will have bipartisan support after the presidential election," Poroshenko said. "And I count on the responsible choice of the American people, no matter it would be Republican or Democrat." (cnn/ez)