They say that this facility in Sweden is being used as the training ground for future wars.
Radio Sweden talked to the people on both sides of this argument.
About a thousand kilometers north of Stockholm lies the Northern European Aerospace Test range (NEAT). It includes a zone operated by the Swedish military, and used by a number of countries, including the US, for testing their warplanes.
And that's what's prompted protesters from around the world to come to a peace camp, set up in the nearby city of Luleå. According to their slogan, "war starts here" - and they say they aim to stop it.
Today, Tuesday, they've announced a day of action - civil disobedience - and are breaking their way onto the base in a show of defiance, as well as painting parts of the test ground pink.
News agency TT reports that ten activists have been arrested.
When Radio Sweden talked to a spokesman from the Swedish military earlier, he said that he was not concerned by the protestors, and that there has been military testing in this part of Sweden for more than 50 years.
Radio Sweden also talked with Linda, one of those hoping to stop the military training ground. The protestors' message is simple - Sweden is being used as a training ground for the wars of the future.
The test range describes itself as secure, independent and available - a place where new equipment can be tested, including firing live weapons. But the campaigners setting up near Luleå want to nip the military in the bud, before the bombs drop for real.
But what about UN-backed peacekeeping, like the intervention in Libya? Linda says that, althou it can sometimes be justified, she thinks that using violence often only brings more suffering.
Some of the demonstrators are being housed in local supporters' homes. But Luleå is a city of just 45,000 people, and the military is the fourth biggest employer. So how welcoming are the local population?
"We have heard views from both sides," says Linda, adding that she is from the local area herself.
Ulf Lindström from the Swedish military said to Radio Sweden that the locals view the test range as a provider of jobs. That he does not see the protest camp as a sign of any wider feeling in Swedish society against the military testing, and that currently there are no military tests going on at the site.