However, if the german 8 inf are placed on UKR, you can strafe them with everything Russia has in range and then retreat to Karelia (leaving 1 Rus. inf in Caucasus). This makes it impossible for Germany to take Karelia on turn 1 unless the use all their planes leaving UK with enough of a navy to take Karelia back on the second turn or do other damage like that.
This is 1 defense that wont work and will lose for the allies most of the time. The only way to go if you want to stay in Len is making no land attacks in Europe. This is already pretty risky. If you do attack chances for allied succes will go down, and attacking Ukr is one of the worst options.
The Russians might opt for attacking Fin w/3 inf, 3 arm, 1 ftr and clearing the BAL sz w/sub, trn, ftr. Picket Len w/1 inf, move aa out of Len and buy 3 inf, 3 arm. All eastern units rush to Mos, and setup for a counter attack on Len. This is quite risky as well, b/c the Japs can send air support to Len after Germany took Len on G1 (ftr Man, ftr Bur, bmb Jap).