As the Allies' attitude in the event of action by Italy, for example attack on Yugoslavia without entry into the war on German side, is now under consideration and your views will be invited , am sending the following rough points for and against immediate declaration of war against Italy placing those 'for' first and those 'against' second.
1. Would restore Allied prestige. Would not restore Allied prestige. Would add to number of our enemies. Italy's aim may be to bring about a dispersion of our forces.
2. Although the Allies could not bring immediate aid to Yugoslavia they could take other action against Italy and prevent the position sliding in South-East Europe. Any action against Italy would be relatively ineffective and we would see Yugoslavia rapidly overrun.
3. Having been successful in Yugoslavian adventure Italy will choose the time which suits her best to enter the war on Germany's side. So long as the Allies not actually at war with Italy there is a hope that Hitler and Mussolini will quarrel.
4. Italy in choosing an attack on Yugoslavia rather than coming into the war on Germany's side has done so because it suits her best, war being unpopular with the Italian people. Declaring war against Italy would consolidate people behind Mussolini and as Allied action would be economic it would revive the cry of sanctions.
5. If the Allies delay in declaring war Italy will have an opportunity to build up her stocks and improve her organisation.
So will the Allies.
6. Although the Allies' offensive action would be limited, would close the entrances of supplies to Italy and would cut off Abyssinia. Italy would be able to interfere seriously with our shipping and by offensive action might achieve success against Malta, Tunisia and Egypt.
7. Would bring Turkey in. While Turkey would no doubt honour her obligations and come in she would do so unwillingly.
8. The Allies would make their blockade against Germany more effective. Allies would also be embarrassed if they would not be able to get oil supplies through from Rumania and substitute purchases would increase strain on dollar exchange.
9. Until Italy knocked out help to Turkey would be difficult in the event of a German push [to] Mediterranean or against the Dardanelles. No certainty that Italy would be knocked out and Allies' sea routes in providing their requirements would be greatly extended.
10. Italy would be a liability to Germany both economically and militarily. Italy might be able to bring Spain in against the Allies.
I am sending some comments on the above in separate cable Number 298.