By April, 2015, Vladimir Putin saw the perfect storm gathering in American politics and decided to seed the clouds. The man is no dummy. He was after all ex KGB, although much like ex Marines, they don't exist. He used his 'cold war' network and long perfected covert craft, to effect a perfect plan (apparently) to critically damage American democracy and throw its government and its people into chaos.
From all apparent accounts, his plan was fairly simple. The first part included the infiltration of both political parties and their candidate's campaign by agents of the Russian government and 3rd party associates for the purposes of extracting intelligence while offering support in the form of fabricated misinformation and other enticements to solidify the infiltration and 'compromat'. The human intelligence gathering did well until the obfuscation failed and their intentions and motives were exposed.
The second part of Putin's plan was to use America's own deep political divisions as a weapon against themselves. Putin was well versed on America politically. He understood that while there were only 2 parties, those parties were divided into thirds. His plan would rely on the widening divide between the left and right in each party to swallow the center. The larger political left/right divide would follow suit and swallow it's center as well. In truth, part of this plan had been in operation for decades, institutionally funding organizations covertly that were 'politically connected'. Again all while gathering political intelligence on hot button/3rd rail issues and buying influence into those circles and their network's politically connected circles. He knows how to work American politics.
The third part of his plan involved us, we the people. How we get our news, who we get if from, our likes and hates, our astuteness and our gullibility. He would use our own media to implement and weave his web of counter intelligence and misinformation, using our cable networks and multi-media, social platforms and Americans, both willing and unwilling as dupes. He was confident the cyber media operation he sanctioned would weaponize and use to his advantage the lunacy exhibited by the 17 or so Republican candidates and the alleged DNC election improprieties as well as the loud cries from the masses of unfairness towards the other Democratic candidate Bernie Sanders. Putin's intelligence gathering also gave him high confidence that the Clinton campaign and the DNC had damaged the Democratic left and the Republicans themselves had damaged their platform and the RNC, to the extent they were basically made moot entities. He privately gloats in Kremlin circles that his continued funding of his prized cyber intrusion operation into America's election system easily mitigated any risk of Clinton winning and Trump losing the election. He's especially proud that he did it utilizing our own 4th estate and our TV and cable multi-media social platforms, After all, he is ex KGB, he's had decads to control his own people and the people of other nations he's directed his aggression towards.
There you have it. That's how it happened. Now...the race to remove the entire episode from the annals of American history. It's much too embarrassing to think about.