That the US President's former confidante and lawyer would emerge as a key player was beyond almost everyone's imagination. Indeed, if Michael Cohen can show federal prosecutors credible evidence that Donald Trump knew in advance about the infamous Trump Tower Russia meeting of June 9, 2016, the President's son could be facing charges of perjury. It was Donald Jr who approved the time, location and participants in a meeting that included a Russian lawyer, Natalia Veselnitskaya, and a Russian-American lobbyist, Rinat Akhmetshin. He also brought to the Trump Tower conference table the then-chairman of Trump's campaign, Paul Manafort, and brother-in-law Jared Kushner among others. The President has repeatedly denied being told about the meeting before it happened. He has said this to the press and the public, recently via Twitter, but apparently never to federal investigators or under oath. Under the circumstances, if Cohen's claim is corroborated (a big "if"), this may be a reprehensible lie; but it's not necessarily criminal. Still, it is so serious that it could theoretically give special counsel Robert Mueller the leverage to propose a deal: Resign the presidency in exchange for immunity for Don Jr. Otherwise, Don Jr will be indicted for lying to the Senate Judiciary Committee, and could, again, theoretically, go to jail. Prosecutors will argue that he was anticipating "dirt" (on Hillary Clinton) from Don Jr's scheduled meeting on June 9 with Veselnitskaya. In such a high-stakes chess game, though, the President could respond by pardoning his son and appealing to the Republican Congress to fight off Democratic impeachment efforts. Hypothetically, the Republican Senate could, even in the face of clear proof of perjury, refuse to seek a criminal referral of Donald Jr's perjury charges for trial. As long as the Republicans maintain a congressional majority, the President may well survive this battle. If the Democrats take control of Congress in November, any Cohen testimony against the President could supply critical ammunition to support an impeachment effort in 2019. This first volley of shots fired by Cohen, the President's former personal lawyer, and renowned "fixer", suggests that he may have additional evidence to sink the Trump presidency. Even more ominous as federal prosecutors empanel a grand jury in the Southern District of New York, the President's true Achilles' heel may turn out to be, not collusion with the Russians but perjury by those, including family members, who may have lied to protect him or the Trump Organisation. A storm is brewing that may be big enough to put the Trump empire under water, taking the Trump presidency with it. Before that storm comes close, it is small wonder that Trump keeps reiterating everywhere that there was no collusion with the Russians. And, why is he so against the Mueller investigations?