Passing the Carrie Fisher Building at Pinewood Studios outside London while filming “Star Wars: Episode IX” is a bittersweet reminder for Oscar Isaac that the legendary actress is never far from his thoughts.

It “always” feels like she’s around while cast and crew are filming the final chapter of the long-running Skywalker saga, Isaac says. “Of course she’s with us.”

“Episode IX” (in theaters Dec. 20, 2019) is the first “Star Wars” film for Isaac, Daisy Ridley, John Boyega and the rest of the returning “The Last Jedi” cast since Fisher’s death in 2016.

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Returning “Force Awakens” director J.J. Abrams “seems to me just as excited if not more so because now there's a history there, there's a shorthand, and the nature of the story is different,” says Isaac, who reprises his X-wing pilot Poe Dameron in "Episode IX" as well as this fall's animated series "Star Wars Resistance."

Abrams will use unused footage of Fisher as General Leia Organa in the new movie, which will also continue the journey of Poe, whose path to leadership in the Resistance was a bit rocky in “Last Jedi” thanks to a few mutinous actions.

“You want to get people (to question him) as opposed to have some sort of easy answer of like, ‘Yeah, yeah, he did the right thing. He was a hero.' What's the cost of this stuff?” Isaac says during an interview for his new thriller “Operation Finale” (out Wednesday).

In the battle against the evil First Order, Isaac thinks it’s easy to forget that the Resistance “are guerrilla fighters, adhering closer to something like the Revolutionary War fighters or even the guerrillas in Cuba with Che and Fidel and all these guys living in the mountains, coming down to do some attacks, and going back and trying to hide from the 'empire' of the United States. It's that kind of ragged at this point.

“You hear about stories with (George) Washington as a general, where lots of people died based on their orders,” Isaac adds, “but that is part of leadership and that push-and-pull in the fight for figuring out what's the way to move forward.”

Not that being a leader doesn’t mean Poe can’t get his hands dirty sometimes. Isaac trained with military advisors for the upcoming Netflix action film “Triple Frontier,” co-starring Ben Affleck and following a group of special-forces operatives who reunite to take down the leader of a South American drug cartel, and he wants Poe to show off some of those new skills in “Episode IX.”

“It is a war movie,” Isaac says. “I mean, above and beyond, it is a movie about warriors.”