Here are my optimized purchases for the first 4 rounds of play as allies in almost every game where I go KGF. This assumes there is a bid of 9, which is fairly standard.
Round 1
USSR: 2 armor 4 inf
UK: 1 art, 2 inf, 2 fig
USA: 2 bombers 1 destroyer 1 transport
Round 2
USSR: 1 art, 8 inf
UK: 1 armor, 2 inf, 2 fig
USA: 3 bombers, 1 transport
Round 3
USSR: 9 inf
UK: 2 inf, 1 art, 2 figs
USA: 1 bomber, 4 inf, 2 transports
Round 4
USSR: 1 art, 7 inf
UK: 8 infantry 1 transport (this one really depends on German buys and if you can defend your fleet)
USA: 2 bombers, 2 inf, 1 transport
Russia just holds West Russia for as long as he can, and the R1 buy of 2 armor helps keep Germany out of Karelia.
UK needs to hold India for as long as possible. The fighters help defend either West Russia or India, and can be really nice for offense as well.
US’s goal is to do damage as fast as possible and bombers are the best for that. Your goal is to get up 7 bombers (this is for LL games). 1 bomber hits southern Italy and the other 6 hit Germany. You need to build at least 1 bomber a turn after you have reached 7 bombers because you will auto loose 1 bomber every time you bomb Germany. US should has his entire pacific fleet to help him defend his fleet of transports.
What this essentially does is make it to where Germany can’t take Western Russia, and he has to worry about landings from UK/US. Germany by turn 5 should be experiencing major factory damage from US’s bombing runs.
The key to this play is to know when to evacuate India. If Germany pushes hard he can eventually West Russia, and with Japan in Russia’s back door you will have immense pressure on you. If you see it coming retreat India and you should be fine. This is likely when you will be using your money on making landings anyways. Make sure US is landing guys in Africa every turn from turn 2 onward. These men will help defend Africa from Japan, and will give you a powerful shuck into Europe later in the game.
This strategy is best in LL, but I think it works well with dice also. I’ve tried US just building transports and troops, and the problem I always run into is that I can’t make a landing anywhere in Europe, so my guys don’t have much of an impact. While bombers, on the other hand, give you immediate damage to Germany and lessens Germany’s ability to wage an effective war vs Russia.
Hope this works for you guys! :)