The UK invaded and occupied Iceland in WW2 after the country claimed neutrality.
The invasion of Iceland by the Royal Navy and Royal Marines occurred on 10 May 1940, during World War II. The invasion was performed because the British government feared that Iceland would be used by the Germans, who had recently overrun Denmark, Iceland's possessing country. The Government of Iceland issued a protest, charging that its neutrality had been "flagrantly violated" and "its independence infringed".
At the start of the war, the UK imposed strict export controls on Icelandic goods, preventing profitable shipments to Germany, as part of its naval blockade. The UK offered assistance to Iceland, seeking co-operation "as a belligerent and an ally", but Reykjavik refused and reaffirmed its neutrality. The German diplomatic presence in Iceland, along with the island's strategic importance, alarmed the UK government.
After failing to persuade the Icelandic government to join the Allies, the UK invaded on the morning of 10 May 1940. The initial force of 746 Royal Marines commanded by Colonel Robert Sturges disembarked at the capital Reykjavik. Meeting no resistance, the troops moved quickly to disable communication networks, secure strategic locations, and arrest German citizens.