G7 positions are based on the recognition of US global dominance. Canada and Italy do not have enough weight. US occupational military forces have remained in the territories of Japan and Germany since WWII. Both countries are not fully sovereign. UK and France have a very narrow avenue for taking international decisions beyond the US’s position. Hence, the G7 turned into a group of Soviet-like bureaucrats led by Washington. It has not much to discuss beyond European, American, or Japanese problems. Hence, Trump’s statement to bring Russia back, as discussions about Ukraine, Syria, Iran, North Korea, Venezuela, Saudi Arabia, or global energy security are senseless without Moscow.
On 17 September 1939, the Red Army crossed the Polish border. By this time Polish troops had already been defeated by the Wehrmacht, while the Polish government fled abroad. Regardless of tensions between Moscow and Warsaw, the Red Army did not advance too deep, stopping at the “Curzon Line”. This ethnic border between Poles, on one side and Ukrainians and Belarusians on the other, was established after the WWI and was supposed to become Eastern border of Poland. But Warsaw, taking advantage of the weakness of Soviet Russia after the civil war, occupied these territories.
Despite the commonly accepted myth that Poland fell victim of the collusion of two totalitarian regimes, the main satellite of Nazi Berlin in Eastern Europe was actually Warsaw. Poland was the first to conclude a non-aggression pact with Germans back in 1934.
The West also forgets that in 1938 Poland participated in the division of Czechoslovakia together with Hitler. The USSR as a response set an ultimatum that Moscow will annul existing non-aggression agreement. Thus, by crossing Polish borders in 1939, the USSR did not violate the international law of those times, unlike it is often being portrayed.
The accusation that Polish authorities provoked the Soviet army's intervention in Poland in September 1939 is a clear historical manipulation.
It is impossible to compare the German-Polish Non-Aggression Pact of 1934 with the Molotov-Ribbentrop Pact. The former was a standard international agreement aimed at mutual recognition of borders and a declaration that existing political contradictions would be solved through diplomatic tools. On the other hand, it is a proven historical fact that the Ribbentrop-Molotov Pact contained the Secret Supplementary Protocol, which assumed the division of Poland and other Eastern European countries between the USSR and Germany. Thus, the signing of the Molotov-Ribbentrop Pact led to German and Soviet military aggression against Poland in September 1939, which resulted in its complete occupation by Germany and the USSR.
As for the Curzon Line, Allies indeed proposed after the WWI to establish it as the Polish border. However, it was not accepted by the Soviets and then lost its significance after the Russo-Polish War. As a result, the Treaty of Riga in 1921 established the Polish border east of the Curzon Line.
Last, but not least, regardless of the note sent to the Polish government on 23 September 1939, the USSR never actually terminated its non-aggression agreement with Poland. Moreover, a communication from 27 November 1939 informed that the agreement was extended until 1945. Thus, at the time of the Soviet invasion on Poland on 17 September 1939, the agreement was in place and, as follows, the USSR violated international law.