Although Ireland was officially neutral, after the German Blitzkriegs of 1939–40 that resulted in the defeat of Poland, the Low Countries and France, the British recognised that Germany planned an invasion of Britain (Operation Sea Lion) and were also concerned about the possibility of a German invasion of Ireland. German planning for Operation Green began in May 1940 and the British began intercepting communications about it in June. The British were interested in securing Ireland, as its capture by German forces would expose their western flank and provide a base of operations for the Luftwaffe in the Battle of the Atlantic and in any operations launched to invade Great Britain as part of Operation Sea Lion.