Never heard of Nena, but she’s got some chops and moves.
One commenter on YT wrote “The German lyrics for the song are about two countries at war with each other. One of whom sees the balloons and assumes they’re under attack. They send out fighter pilots, the other country responds. War ministers in each country encourage the war as a power grab.”
It's all over, and I'm standing pretty
In this dust that was a city
If I could find a souvenir
Just to prove the world was here
And here is a red balloon
I think of you, and let it go
The English version the same, but it is clear the bad guy is the US, with its “President” (evil Reagan!) happily declaring they’re going to war.