dRump/Putin "friendship"
Putin was KGB and when the Soviet Union fell, he lost his country, so to speak. His lifes work, since the fall of the Soviet Union, is to return it to superpower status and higher prestige. His secondary ambition is to reduce the U.S. in status and actual power.
Because of the invasion and territorial grab in the Ukraine, Crimea and elsewhere, Russia was put under sanctions. Russians, over more than a years time, hacked the DNC, private emails, states election boards, etc. The U.S. intelligence community discovered this and announced their findings in the summer of 2016. In addition, Russia also hacked the elections in Britain, Germany, France, and Spain. And the Russians were again sanctioned.
The sanctions had handicapped the Russian economy and the movement of money by the oligarchs. dRump is a bumbling nepotistic idiot. He was born on third base and claims to have hit a triple. Putin needed a willing fool to act for him. dRump, who had an affinity for oligarchy and a preternatural desire for a Trump Tower in Moscow, fit the bill and the Putin/dRump friendship was born.
As Putin had thrown in with dRump, some quid pro quo was needed. The promise, the tactical gain, the quid pro quo was a Trump Tower for lifting of sanctions. Flynn tried to help and he fibbed to the FBI about what was discussed.
As always, the overarching strategic goal for Russia and Putin was freedom to continue oligarchic business as usual and the diminution of prestige and power and especially the projection of U.S. power in the world. With dRump, he gets that everyday. And this is where we stand today.
Facts with some speculation.