The Russian historian Stephen Kotkin describes Russia as a paradox; it is a weak major-power, run by a criminal regime. Russia has a muscular arsenal, a strong state department and a world-class intelligence service. They have no real allies.
The Russian foreign policy is to be aggressive and daring, to destabilize the outside world; "a strong offence is a good defence."
What did Russia want in the 2016 American election?
They wanted to discredit American-style democracy in the eyes of the world.
Russia did not collude with the Trump campaign. Instead, they entangled them with criminality so that the internal American legal structure would tear apart the ruling government. It was an auto-immune attack. They were going to use the American rule of law against itself, to distract, and even lobotomize the American executive branch. It was a very successful operation:
Stephen Kotkin also describes why Trump has a "red-line": the American government was not to look into his business practices. Donald Trump built his fortune laundering money, by letting criminals park their cash in expensive real-estate: