Actor Sean Penn may be home from Ukraine, but he's still got the country on his mind amid Russia's invasion.

Over the past several months the filmmaker spent time in Ukraine to film a documentary featuring President Volodymyr Zelenskyy and military forces. Although he's since returned home to California, Penn revealed in a new interview that he has intentions to go back and has thought about "taking up arms" against Russia.

"The only possible reason for me staying in Ukraine longer last time would’ve been for me to be holding a rifle, probably without body armor, because as a foreigner, you would want to give that body armor to one of the civilian fighters who doesn’t have it or to a fighter with more skills than I have, or to a younger man or woman who could fight for longer or whatever," Penn told Hollywood Authentic.

"So, where I am in life is short of doing that, but if you’ve been in Ukraine [fighting] has to cross your mind. And you kind of think what century is this? Because I was at the gas station in Brentwood the other day and I’m now thinking about taking up arms against Russia? What the f--- is going on?" Penn, 61, continued.

SEAN PENN SPEAKS OUT ABOUT TIME IN UKRAINE, SAYS ZELENSKYY 'WILL WIN, BUT AT WHAT COST'

Sean Penn visits Ukraine

Actor and director Sean Penn visits positions of the Ukrainian Armed Forces near the frontline with Russian-backed separatists in Donetsk region, Ukraine, in this handout picture released by the Joint Forces Operation press service November 18, 2021.  (Reuters)

Penn arrived in Kyiv to film about the escalating conflict when Russia's war on Ukraine broke out in February. He also met with Ukrainian President Volodymyr Zelenskyy, who announced the star's presence on social media.

"American actor and film director, Oscar winner Sean Penn arrived in Ukraine," read a translated statement from the Office of the President of Ukraine’s Facebook page. "The director came to Kyiv specifically to record all the events taking place in Ukraine as a documentary filmmaker and to tell the world the truth about Russia's invasion of our country."

Penn now credits Zelenskyy for uniting the entire country of Ukraine.

"They are together like never before and, as I said, that’s the historical legacy of Zelenskyy, because he’s the man who did it. They’ll never be able to take it away from him that he unified the Ukrainians to fight for their country," Penn said of the president.

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He recalled first meeting Zelenskyy before Russia's invasion, and at the time believed he had met a man who was "very charming, and very bright and very charismatic." Penn said he remembers war was not something anyone was completely "convinced" about before it happened. Still, he saw a shift in Zelenskyy once the invasion began.

"So, seeing Zelensky the day before invasion, I would say, it serves to reason that he would not have felt fully tested. And then seeing him the next day, it struck me that I was now looking at a guy who knew that he had to rise to the ultimate level of human courage and leadership. I think he found out that he was born to do that," Penn said.

Ultimately, Penn said, his "intention is to go back into Ukraine." But he's not so quick to do so because "I am not certain what I can offer," he explained.

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Sean Penn Ukraine press briefing

Actor and director Sean Penn attends a press briefing at the Presidential Office in Kyiv, Ukraine February 24, 2022.   (Ukrainian Presidential Press Service/Handout via REUTERS)

"I don’t spend a lot of time texting the president or his staff while they’re under siege and their people are being murdered. I’d probably send one message through the chief of staff. ‘Here’s what I’m looking to do that I think would be of value. You only have to answer me in one of two ways: don’t come or come and do what you’re planning, or come, but here’s where you could be more helpful,'" he said.

Through his nonprofit CORE, Penn is still helping refugees in Poland. In addition, he is still working on his documentary, but in the same breath said he is questioning its purpose.

"People will argue this, and there’s a million debates that I understand, but long term, we don’t have any tangible evidence that documentaries really change anything. We just don’t. We only know they can give hope," he said. 

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Sean Penn Ukraine

Sean Penn was in Ukraine when Russia first invaded the country in February. (Reuters)

Elsewhere in his interview, Penn touched on his wife Leila George, who filed for divorce from the actor in 2021.

"I don’t know what’s going to happen with us, but I know that this is my best friend in the world and definitely the most influential, inspiring person, outside of my own blood, that anybody could ask to have in their life," he said.