U.S. President Donald Trump has expressed rare frustration with Russian President Vladimir Putin, saying he is “very angry” and “pissed off” over stalled cease-fire negotiations in Ukraine. In a phone interview with NBC News on Sunday, March 30, Trump criticized Moscow for adding new conditions to a U.S.-backed peace deal, delaying efforts to curb attacks in the Black Sea and on energy infrastructure.

Previously known for praising Putin and even questioning Ukraine’s stance in the conflict, Trump took a more aggressive tone, condemning reports that Putin demanded a transitional government to oust Ukrainian President Volodymyr Zelensky. According to AFP, the Russian leader also suggested that Ukraine’s military remove Zelensky themselves.

“If Russia and I are unable to make a deal to stop the bloodshed, and if I determine Russia is at fault which it might not be but if I think it is, I will impose secondary tariffs on all Russian oil,” Trump warned. “If you buy oil from Russia, you can’t do business in the U.S. There will be a 25% to 50% tariff.”

Trump set a one-month deadline for a cease-fire deal before implementing the tariffs. Despite his harsh words, he maintained that he still has a "very good relationship" with Putin, saying his frustration would subside if the Russian leader “does the right thing.”

The two leaders are expected to resume talks this week. Meanwhile, the Trump administration continues efforts to broker peace, having secured two cease-fire agreements last week both of which Russia reportedly violated within hours before demanding sanctions relief from Europe.