Gonna go ahead and say it, the Molotov-Ribbentropp pact was unironically a good thing given the circumstances (Britain and France both refusing to enter into an anti-fascist alliance with the USSR). A master stroke of diplomacy that forstalled the inevitable and gave the Soviet Union time to develop and arm.
It also let the Soviet Union take back territory that had been stolen during the Polish-Soviet war and save a big chunk of Poland from Nazi rule.
Also like 2 of them are even smiling, pretty sad "celebration". Looks to me like on both sides even ordinary troopers knew they are enemies with eachother.
While for example, this happened while Soviets and Americans met, when both side soldiers genuinly considered themselves allies: