Addressing the U.N. General Assembly Wednesday evening, Yatsenuk delivered a direct message to Russian President Vladimir Putin.
"Mr. Putin, you can win the fight against the troops, but you will never win the fight against the nation - united Ukrainian nation," said Yatsenyuk.
Yatsenuk said that Russia has violated international laws by invading parts of its territory, arming pro-Russian insurgents and annexing the Crimea peninsula in March.
Earlier Wednesday the Ukrainian prime minister spoke at the Council on Foreign Relations in New York.
He expressed skepticism about the cease-fire with pro-Russian rebels, calling it extremely fragile and shaky.
He said Ukraine could easily deter separatists and restore peace in the country.
But he said its armed forces cannot fight against the well-trained and well-equipped Russian military.
Although Moscow denies it, there has been ample evidence of direct Russian military support for rebels in eastern Ukraine, and the presence of Russian troops on Ukrainian soil.
NATO, which has observed some pullback in recent days, says some Russian troops still remain.
Yatsenyuk is blaming Russian President Vladimir Putin personally for arming the separatists in eastern Ukraine.
"And this is President Putin who personally sent his military and his agents, his heavy weapons and artillery, his lethal weapons and lethal aid to Ukraine," referring with “lethal aid” to three humanitarian convoys Russia sent into Ukraine, parts of which, Kiev says, Moscow used to ship in supplies and reinforcement for rebels.
Yatsenyuk said economic sanctions against Russia are effective, that the value of the Russian currency, the ruble, has dropped, and that inflation there is on the rise.
But he said while sanctions work in the long run, Ukraine needs a short-term solution to prevent Russia from taking control of eastern Ukraine and moving farther inland.
He said the ultimate goal of the Russian president is to create another frozen conflict in Europe.
One such conflict, widely seen as supported by Moscow, is in Moldova's Transdniester region, which borders Ukraine.
Some observers have suspected that Putin’s ultimate plan, after annexing Ukraine’s Crimea in March, would be to establish a land corridor along Ukraine’s Black Sea coast connecting Russian mainland with Transdniestria, as the Moldovan region is also known, thus also securing Moscow’s land access to Crimea.
Currently, Crimea is accessible to Russia only by land and sea, and depends heavily on electricity and drinking water provided by Ukraine.
Yatsenyuk said he would like to see U.S. and EU participation in talks with Russia on settling the conflict.
As for the long-term, Ukraine’s prime minister said that he believes the time will come when peace will be reestablished in the country’s east, Crimea will return under Kiev’s control and Russia will apologize for its actions.
But he ruled out that this would happen under Putin.
Source: Voice of America