Sadly, neutrality is rarely enforceable. Belgium was neutral before WWI, but this was brushed aside for strategic reasons.
During WWII, Swedish neutrality was also under threat. Initially, the Germans would only allow Swedish neutrality to remain in operation if German troops were given access to Swedish ports and railway systems, which the Swedes acceded to. The Swedes were also in two minds about remaining neutral when the Russians invaded Finland.
Sweden was also considered a viable staging post by allied commanders for an invasion of Denmark and the Germans once again considered invasion to prevent this.
Neutrality enabled the Swedes to liase between the axis and the allied powers, but their neutrality would probably be ignored in any future conflict because it is now accepted that Swedish diplomats spied for the allies when visiting Germany.