I'm looking for a movie where in the end the Earth is destroyed by aliens

Question

There was a movie I saw maybe 7-8 years ago (2007-2009). I don't know which year it was, but I guess it's not such an old movie. it's a sci-fi movie but not with aliens like we know -- actually I don't remember any alien. Until today, I thought that the main star was Michael Keaton, but I searched his list of movies and didn't find this one.

He is like someone that works in security for the government and has been called for duty because of some suspicious things that happens. There's a big part in this movie where he is in some kind of a chase in some city underground & there's a scene where he meet some man that helps him. What i remember the most is the end.

In the end of the movie, there's some twist when he finds out that the aliens fooled him & made him one of them & just a few seconds after he realize that he understands that and simultaneously he understands that Earth is going to be destroyed in a few seconds and that's how the movie ends.

Answer 1

A bit longer ago than 7 -8 years but this sounds a lot like the 2001 film Impostor with Gary Sinise.

Points that match:

it's a sci-fi movie but not with aliens like we know:

The movie takes place in the year 2079. Forty-five years earlier, Earth was attacked by a hostile and implacable alien civilization from Alpha Centauri.

-- actually I don't remember any alien.

The Centaurians have never been physically seen.

He is like someone that works in security for the government

Gary Sinise plays Spencer Olham, a designer of top secret government weapons

and has been called for duty because of some suspicious things that happens.

The ESA intercepted an alien transmission which cryptanalysts decoded as programming Olham's target to be the Chancellor, whom he was scheduled to meet.

There's a big part in this movie where he is in some kind of a chase in some city underground & there's a scene where he meet some man that helps him.

As he's about to drill out his chest to find the bomb, Olham breaks loose and escapes, accidentally killing his friend Nelson in the process. With the help of underground stalker Cale, Olham avoids capture and sneaks into the hospital where his wife Maya is an administrator.

In the end of the movie, there's some twist

when he finds out that the aliens fooled him & made him one of them.

In Impostor

such replicants are perfect biological copies of existing humans, complete with transplanted memories, and do not know they are replicants. Each has a powerful "u-bomb" in their chest, which can only be detected by dissection or a high-tech medical scan, since it only assembles itself when it gets in proximity to its target. Detection via the special scan works by comparing against a previous scan, if there was one.

and

At that moment, Olham realizes aloud that he really is a replicant,

Finally you indicated

just a few seconds after he realize that he understands that and simultaneously he understands that Earth is going to be destroyed in a few seconds and that's how the movie ends.

and in the movie not quite as widespread as you indicated but

the secondary trigger (his awareness of what he truly is) detonates his u-bomb, destroying himself, Hathaway, his troops, and everything else in a wide area, in a fiery nuclear explosion.