Complex sentence: Because of the escalating situation further south in Central Russia, the Germans were unwilling to assign more units to this theatre, calling an end to their offensive; the Finns were reluctant to continue the attack on their own due to diplomatic pressure from the United States.
Split into simpler sentences: Because of the escalating situation further south in Central Russia, the Germans were unwilling to assign more units to this theatre, calling an end to their offensive. While the Finns were reluctant to continue the attack on their own due to diplomatic pressure from the United States.