Russian President Vladimir Putin on Thursday defended his decision to sell a long-range air-defense missile system to Iran, criticized the West for its treatment of Moscow, called "tragic" the killing of an opposition figure and said Ukraine was not living up to commitments made in a recent peace deal.

His comments were part of a four-hour call-in TV show that has become an annual tradition.

Putin said Russia was selling the S-300 missiles to Iran because the Islamic republic has shown "a great degree of flexibility and a desire to reach compromise" in talks with six world powers, including Russia, over its nuclear program. He said the missiles did not pose a threat to Israel, adding it served as "a deterrent factor" to the situation in Yemen, where a Saudi-led campaign is targeting an Iran-backed Shiite militia.

Putin also discussed the situation in Ukraine, where Moscow-backed separatist rebels are fighting the government in Kiev.

"There are no Russian troops in Ukraine," he said in response to a question.

There have been reports of Russians fighting among the rebels and Russian military systems inside rebel territory.

And when he was asked if a war between the two countries was likely, he said "a war ... is impossible."

Putin described Ukraine as a "brotherly nation," adding: "I make no difference between Ukrainians and Russians in general. I think this is basically the same nation, ethnically." But he accused Ukraine of violating its commitments to February's peace deal by maintaining an economic blockade on rebel-held areas.

The Russian economy, which has struggled with low oil prices and the impact of Western sanctions because of Moscow's actions in Ukraine, dominated the questions. Putin acknowledged sanctions had had an impact but said the economy was improving.

"Regardless of any sanctions the economy correction was unavoidable," he said. "Those sanctions actually helped the government and the central bank. They could say: 'We do what we do because of the sanctions.' Not just because of them. We have to correct our economic policy in a more professional and vigorous manner."

Relations with the West are at their lowest point since the end of the Cold War, and Putin said that "our partners should at least try to seek compromise rather than put pressure on us."

"The U.S. doesn't need allies, it needs vassals," he said. "Russia cannot exist in such a system of relations."

Putin was also asked about the killing of opposition leader Boris Nemtsov. He called the assassination of the critic of the Kremlin on Feb. 27 "tragic and shameful." Five people have been arrested in connection with the killing.

The translation of Putin's comments was provided by Russia's state-run Russia Today.

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