I think there were lots of different underground levels in the research base.
When the soldiers went in, they found an unhelpful scientist (not a priest) on the first level.
They left him there with a soldier whilst other soldiers went to the lower levels.
They were then pursued by some kind of creature.
Can’t find this film anywhere. I only know that the film was NOT called The Devil’s Tomb. It was a film similar to that, though.
Thanks everyone.
2nd guess:
Alien Lockdown (2004).
https://www.imdb.com/title/tt0395443/
If this isn’t it, could you tell me what the creature was like?
one of the “Xtro” series?
https://m.imdb.com/title/tt0100975/
The movie has been identified. It was Alien Lockdown (2004). But thanks for trying to help. I appreciate it. I will watch those xtro movies, though. I like those kind of movies with aliens and experiments etc.
Maybe:
The Superdeep (2020).
https://www.imdb.com/title/tt11815960/
https://www.youtube.com/watch?v=aO6gYI_LXBo
Very good effort, and thanks for replying. But it’s not The Superdeep. I’m pretty sure the movie I am looking for is older than that. Thanks again.
Yes. That is it. I’ve just watched it. Well done mate. Thanks for your help.