Wary of the perceived threat from Russia, the countries that make up the Nato Western military alliance are upping their spending on the military. But not fast enough, according to former US president Donald Trump, who has made the issue part of his election campaign.
So should governments in Europe be spending more on their collective defence? Do Europeans want them to, or would they rather that money go to things like education and healthcare instead?
As Sweden joins the alliance, we look at who is spending what within Nato, who is pulling their weight, and who is not.
We speak to people across Europe about what they want, and we talk to one former army chief, who says his country is woefully underprepared to defend itself.
Presenter/producer: Gideon Long Additional reporting from Bethany Bell, BBC correspondent in Vienna And additional recording by Maddy Savage in Stockholm and Kostas Kallergis in Brussels
(Photo: German Eurofighter Typhoon jets of TLG73 during Nato exercise. Credit: Getty Images)