An interstellar craft is a potential weapon. If your society has FTL travel it has the power to inflict tremendous damage on other societies, and if those other societies also have FTL travel they will have also calculated the potential destructiveness of FTL ships.
A starship doesn't need ray guns and missiles to devastate a planet. The crew can just program the navigational computer, leave in lifeboats, and let the ship ram into the planet at high speed.
Or maybe they could program the ship to ram into the planet's star at high speed and disrupt the star, dooming all life on the planets of that star.
Or a starship could match orbits with and attach itself to an asteroid or comet or change the course of that asteroid or comet, then go to another asteroid or comet and change its course, and do it again and again and again until tens or hundreds of asteroids and comets, each large enough to devastate the planet, are headed on collision courses with the planet.
I remember an article in which a scientist who thought the idea of interstellar travel was silly calculated that if a slower than light interstellar rocket ship launched from Earth using full power the energy in its rocket exhaust would be enough to kill all life on Earth.
You may have heard of the theoretical Alcubierre warp drive. I have read that a ship using that warp drive would accumulate matter and energy as it traveled, and when it turned off the warp drive that matter and energy would be discharged in a blast that would devastate any planet it hit.
If so, a starship using that warp drive would have to stop to discharge energy in interstellar space and restart several times during an interstellar voyage in order to preserve the destination. But a warship headed to another planet to destroy it would leave the Alcubierre drive on for the entire trip to built up energy for a blast to destroy the target planet at the end of the voyage.
So societies which have interstellar travel will no doubt know how dangerous starships can be, and they will react to such knowledge. Perhaps they will have laws and regulations requiring all ships which approach their system to travel at specific courses and speeds.
in the Star trek: The Next Generation episode "Haven", an unidentified spaceship approaches the planet Haven from interstellar space, and the ruler, First Electorine Valeda Innes, asks help from Captain Picard of the Enterprise:
VALEDA [on viewscreen]: An incoming vessel has bypassed our stargate, violating our law. It has refused any attempt at communication.
PICARD: Are you saying you believe it to be hostile?
VALEDA [on viewscreen]: Failure to communicate is inherently hostile. We have no defensive capabilities here and our treaty with the Federation specifies your obligations in that matter.
I don't know what the stargate was, nor exactly what bypassing it means, but obviously Valeda Innes considers approaching in an unusual manner to be extremely threatening.
I don't know whether Tracy Torme and Lan O'Kun, the writers of "Haven", were thinking of the real life danger potential of starships when writing those lines, but they might have been.
Another way interstellar civilizations might react to the potential dangers of starships would be with massive planetary defensive systems for every important planet. They would have gigantic ground based ray guns and missile launchers and force field generators, and gigantic ray guns and missile launchers and force field generators in low orbit around the planet, and gigantic ray guns and missile launchers and force field generators in high orbit around the planet, and gigantic ray guns and missile launchers and force field generators in orbit around the entire solar system, and so on.
In Second Stage Lensman in E.E. Smith's Lensman series, the space fleets of two entire galaxies fight a battle. One fleet destroys the millions of space battleships in the other fleet. But the victorious fleet with millions of space battleships doesn't dare to attack the planet Onlo with the super powerful defense system of Onlo.
And if interstellar travel ever becomes a reality, it is probable that most societies with interstellar capabilities will build defense systems as powerful as Onlo's to protect their important planets and solar systems against attacks by foreign space navies or by terrorists using hijacked civilian starships.
So if your planet knows about interstellar travel and doesn't build a super defense system against interstellar war and terrorism your neighbors are likely to think that they have a short window of opportunity to invade and conquer your planet before you wise up and start building a super powerful planetary defense system.