Aug. 23 (UPI) -- Paramount+ announced Wednesday that the documentary Superpower will premiere Sept. 18 on the streaming service. Sean Penn and Aaron Kaufman made the documentary about Ukrainian president Volodymyr Zelensky.

Penn and Kaufman filmed the documentary in 2021-22 while Ukraine fought off Russian forces. Penn began filming Zelensky to learn more about the former actor and comedian turned presidential candidate.

After Zelsnky's election, the film captured Putin' first rocket attack and and aftermath as Zelensky led Ukraine's resistance. Penn spent the night of the first attack in Zelensky's bunker.

"We set out to tell a lighthearted tale of this comedic actor who had been elected President of Ukraine and instead became witness to a historic leader and his country's war for freedom," Penn said in a statement.

"When you step into a country of such incredible unity, you realize what we (in the United States) have all been missing," Penn continued.

Superpower previewed as a work in progress at the Berlin International Film Festival.

Penn also interviews veterans of the 2014 invasion and visits the front lines of the current war, and the citizens affected in their homes. In the trailer, Penn offers to help survivors sort through wreckage in their home.

Penn also co-founded the disaster relief charity CORE and personally assisted survivors and relief workers after the 2010 Haiti earthquake.

Fifth Season and Vice News financed Superpower. Vice Studios and Projected Picture Works produced.

Penn produced with Billy Smith, Sergei Bespalov, Danny Gabai and Lauren Terp, with Executive Producers Kate Ward, Katie Peck, Andrew Freston, Bruce Dixon, Hozefa Lokhandwala, Subrata De, Susan Zirinsky, Terence Wrong, Anthony Gudas, Chad A. Verdi and Sasha Cherniavsky.

Fifth Season will distribute internationally.