Sean Penn Is 'Thinking About Taking Up Arms Against Russia' After Returning from Ukraine amid War

Sean Penn is showing his support for Ukraine amid the ongoing Russian invasion.

After spending months documenting the war, the actor, 61, told Hollywood Authentic magazine that he recently thought about fighting on behalf of Ukraine.

"If you've been in Ukraine [fighting] has to cross your mind," he said in the interview published Saturday. "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?"

Amid the start of the Russian invasion in late February, Penn traveled to Ukraine to work on an upcoming documentary about political tensions, chronicling the invasion and war launched by Russian President Vladimir Putin.

"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 armour, because as a foreigner, you would want to give that body armour 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," he told Hollywood Authentic.

In a statement shared with PEOPLE in February, Penn expressed his thoughts on the horrors that the Ukrainian people are facing.

"[It is] already a brutal mistake of lives taken and hearts broken, and if he doesn't relent, I believe [Russian president] Mr. [Vladimir] Putin will have made a most horrible mistake for all of humankind," he said.

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"President [Volodymyr] Zelenskyy and the Ukrainian people have risen as historic symbols of courage and principle. Ukraine is the tip of the spear for the democratic embrace of dreams," he added.

In his Hollywood Authentic interview, Penn also talked about meeting with Ukrainian President Volodymyr Zelenskyy "the day before the invasion" and being with him "during the invasion, on day one."

Seeing Zelenskyy on that day, he said, "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."

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Russia's attack on Ukraine continues after their forces launched a large-scale invasion on Feb. 24 — the first major land conflict in Europe in decades.

Details of the fighting change by the day, but hundreds of civilians have already been reported dead or wounded, including children. Millions of Ukrainians have also fled, the United Nations says.

"You don't know where to go, where to run, who you have to call. This is just panic," Liliya Marynchak, a 45-year-old teacher in Ivano-Frankivsk, Ukraine, told PEOPLE of the moment her city was bombed — one of numerous accounts of bombardment by the Russians.

The invasion, ordered by Russian President Putin, has drawn condemnation around the world and increasingly severe economic sanctions against Russia.

With NATO forces massing in the region around Ukraine, various countries have also pledged aid or military support to the resistance. Ukrainian President Zelenskyy called for peace talks — so far unsuccessful — while urging his country to fight back.

Putin insists Ukraine has historic ties to Russia and he is acting in the best security interests of his country. Zelenskyy vowed not to bend."Nobody is going to break us, we're strong, we're Ukrainians," he told the European Union in a speech in the early days of the fighting, adding, "Life will win over death. And light will win over darkness."

The Russian attack on Ukraine is an evolving story, with information changing quickly. Follow PEOPLE's complete coverage of the war here, including stories from citizens on the ground and ways to help.