Vladimir Putin Maxim Shipenkov | Pool | Reuters

When you put this all together, there's a clear and demonstrated pattern of contact between Trump's closest associates and Russian officials. That is, in and of itself, disturbing: Political campaigns are not typically in the habit of communicating with countries who are currently bombing US military partners.

And it's not clear, judging by the behavior of the Republicans at the House Intelligence hearing, if our hyper-polarized political system is capable of handling it.

The Russia investigation is absolutely huge

The mere fact of an FBI investigation isn't proof that the Trump administration has actually done anything illegal. But the fact that there is an investigation at all shows the suspicions are at least serious enough to warrant a full investigation. And in this case, the FBI's suspicions are supported by a lot of information that's already in the public record. We already know, for example, that members of Trump's campaign, including former Trump campaign manager Paul Manafort, were in touch with Russian intelligence officers. We know that Attorney General Jeff Sessions, who also served as a foreign policy adviser to Trump during the campaign, met repeatedly with Russian Ambassador Sergey Kislyak before the election. We know that Russian intelligence hacked the emails of the Democratic National Committee and Clinton ally John Podesta. And we know that Trump confidante Roger Stone admits that he spoke to the Russian intelligence cutout who claimed responsibility for the DNC hack (who goes by the name Guccifer 2.0). When you put this all together, there's a clear and demonstrated pattern of contact between Trump's closest associates and Russian officials. That is, in and of itself, disturbing: Political campaigns are not typically in the habit of communicating with countries who are currently bombing US military partners. What's more, there's also a consistent pattern of Trump administration officials being less than forthcoming about their Russia ties. Former National Security Adviser Michael Flynn lied about his contacts with Kislyak, as did current Attorney General Jeff Sessions. The lies cost Flynn his job and forced Sessions to recuse himself from the FBI's Russia investigation. Yet Trump himself continues to deny, in the face of all this evidence, that there's any story here: @realDonaldTrump: The Democrats made up and pushed the Russian story as an excuse for running a terrible campaign. Big advantage in Electoral College & lost! This is why, even if nothing else is uncovered, the FBI investigation is so important. The president's team has links to Russia that are objectively worrying — and has a routine pattern of lying and blaming the media when confronted with them. There's a question of fundamental credibility, of why they feel the need to dissemble, at stake here. The thought that the president may be lying, or at least not being fully forthcoming, about his administration's ties to a hostile power is disturbing enough in its own right. The very fact that the FBI is investigating the administration two months into its tenure shows that things are not going well in the most powerful office in the world. But if the worst-case scenario comes to pass, and the FBI find hard evidence that the Trump campaign was in league with the Russians, then the already-serious scandal becomes a national crisis. "If [there's] coordination, then this scandal becomes Watergate-like," Michael McFaul, the former US ambassador to Russia, tweeted. McFaul, if anything, understated the case. In Watergate, a presidential campaign authorized a break-in aimed at stealing sensitive information from the Democratic National Committee. This would be the exact same thing, only done digitally and with the help of a hostile foreign power. It would represent collusion with Russian President Vladimir Putin to undermine American — and Western — democracy. The notion that a US president could be involved in something like that should seem preposterous. The fact that the FBI is taking it seriously says volumes.

Our political system isn't prepared for this kind of thing