As Britain and France seemed unwilling to commit to an alliance with the Soviet Union, Stalin saw a better deal with the Germans. On 3 May 1939, Stalin replaced his western-oriented foreign minister Maxim Litvinov with Vyacheslav Molotov. In May 1939, Germany began negotiations with the Soviets, proposing that Eastern Europe be divided between the two powers. Stalin saw this as an opportunity both for territorial expansion and temporary peace with Germany. In August 1939, the Soviet Union signed the Molotov-Ribbentrop pact with Germany, a non-aggression pact negotiated by Molotov and German foreign minister Joachim von Ribbentrop. A week later, Germany invaded Poland, sparking the UK and France to declare war on Germany. On 17 September, the Red Army entered eastern Poland, officially to restore order amid the collapse of the Polish state. On 28 September, Germany and the Soviet Union exchanged some of their newly conquered territories; Germany gained the linguistically Polish-dominated areas of Lublin Province and part of Warsaw Province while the Soviets gained Lithuania. A German–Soviet Frontier Treaty was signed shortly after, in Stalin's presence. The two states continued trading, undermining the British blockade of Germany.