Penn is one of a growing chorus now urging Western countries to send Kyiv modern fighter jets ahead of an expected Russian spring offensive. Lawmakers from both parties are pressing the White House to transfer the jets, but President Joe Biden recently ruled it out — at least for now.

On Thursday night, national security adviser Jake Sullivan said the fighter planes aren’t what Ukraine needs right now.

“From our perspective, F-16s are not the key capability for that offensive. It is the stuff that we are moving rapidly to the front lines now,” he said on CNN.

“F-16s are not a question for the short-term fight,” he added. “F-16s are a question for the long-term defense of Ukraine, and that’s a conversation that President Biden and President Zelenskyy had.”

But those pushing the jets aren’t giving up without a fight. Penn was actually one of the first people to call for sending modern fighter jets to Ukraine. As far back as April, he called for a billionaire to buy two squadrons of F-15 or F-16 aircraft for Kyiv. Since then, he has made the case — publicly in TV appearances and in private by pressing members of Congress — that the seasoned Ukrainian fighter pilots should get more advanced aircraft to better protect their homeland.

One of those lawmakers is Rep. Eric Swalwell (D-Calif.), who in the past has tweeted out messages lauding Penn’s support for Ukraine, including one linked to a video showing the Oscar winner giving one of his statues to Zelenskyy. “This is the best of American creative talent helping Ukraine,” Swalwell wrote in November.

A spokesperson for Swalwell confirmed that he has talked to Penn about the fighter jet situation. He could not immediately be reached for comment.

Penn said Biden’s recent trip to Kyiv to mark one year since the Russian invasion is “extremely encouraging,” but urged the administration to continue arming Ukraine, including with modern fighter jets.

“There’s no scenario where Ukraine loses this battle,” Penn said. “There’s a scenario where territory is taken, and Putin buys his way into fighting insurgents throughout a broken infrastructure of a broken country. But the Ukrainians are going to fight till the last drop of blood. And that drop of blood will be on our hands if we don’t faithfully equip them.”

The actor, whose documentary about the Ukraine conflict, “Superpower,” premiered on last week, was actually in Kyiv when Russian forces launched their attack one year ago. Penn recalled how in a meeting on the eve of the invasion, Ukrainian President Volodymyr Zelenskyy agreed to participate in the film.

“We went back to our hotel and closed our eyes for about two hours and all of a sudden, the missiles and rockets were coming in,” Penn said.

Despite the onslaught, Zelenskyy, who features prominently in “Superpower,” honored his promise and allowed Penn’s team in the next day to film. Penn stayed in the country for a few days before evacuating. He’s been back for a total of six visits, including most recently Feb. 13-14 to show Zelenskyy the final version of the film in person.

The Ukrainian president spoke to artists and filmmakers in a live video address at the opening of the Berlin International Film Festival on Feb. 16, where “Superpower” premiered.

While Zelenskyy was “clearly realistic” about the threat of an impending invasion when they met on Feb. 23, the Ukrainian head of state “could not possibly have known that he would so completely rise to the occasion of the actuality,” Penn said.

The next day, Zelenskyy was a changed man whose country was at war.

“It was immediately clear when he walked into the room on February 24th that we were witnessing the newfound embodiment of an historic courage and leadership,” Penn said. “The resolve was in his eyes; Zelenskyy wasn’t going anywhere.”

Penn is the latest celebrity to lend his fame to help Ukraine. This month, “Star Wars” actor Mark Hamill told POLITICO that he plans to sell signed movie posters in order to raise money to send drones to Kyiv.

Over the past year, Penn has become versed in different fighter jets after many discussions with Ukrainian and American pilots on the urgency of upgrading Kyiv’s aircraft. He recently visited Washington, D.C., with a group of Ukrainian fighter pilots, who were there lobbying the Hill. There, he also met with members of the 144th Fighter Wing with the California Air National Guard, which has a 30-year state partnership with Ukraine.

The group discussed how the U.S. could train experienced Ukrainian pilots to fly the American-made F-16 in as little as three months. Penn was particularly struck by the pilots’ argument that the jets could help defend Ukrainian cities and military positions from Russian missile attacks.

“Some of the discussion related to training, fueling, maintenance and compatible munitions — holistic training — is a distraction. You have to force-multiply by dividing the specialization of skills among squadrons. Talk to the [California] National Guard,” Penn said. “It’s about bringing in specialty squadrons to get them up and flying effectively.”

‘It changes the dynamics,” he said, referring to modern fighter jets.

During Penn’s conversations with the Ukrainian pilots, it became clear to him just how outdated their military technology is. While they were in the U.S., they even attempted to buy helmets on Amazon, he said.

The average Ukrainian soldier doesn’t even have a direct communications line to call in an airstrike, Penn said, noting that they have resorted to using their cell phones.

But even with inferior technology, “It’s amazing how toe to toe the Ukranians have been able to defend themselves against those superior aircraft,” he said.