Mr. Trump was impeached in December last year by the House of Representatives on two counts: abuse of power and obstruction of Congress. Now he is scheduled to be tried by the Senate, with the chief justice of the Supreme Court presiding. Nobody expects the Republican-led Senate to convict Mr. Trump, even though it is clear that he abused his power when he sought to pressure the Ukraine into announcing an investigation into his political rival, former US vice president Joe Biden, by threatening to withhold military aid that the US Congress had already allocated—assistance that was critical, given that Russia invaded the Crimean Peninsula and annexed it in 2014, on orders from Mr. Trump’s bosom buddy, President Vladimir Putin. Mr. Trump’s subsequent refusal to permit any of his subordinates to testify during an investigation, and his refusal to release any pertinent documents related to his pressure campaign on the Ukraine make clear, too, that he was guilty of obstruction of Congress. None of this matters, however, to the Republican senators headed by Senator Mitch McConnell, who had made it abundantly clear that he does not intend to conduct an impartial trial, and also said he would be coordinating in lockstep with White House lawyers. With no interest in admitting an inconvenient truth, the senator has even refused to allow any new witnesses to be called during the Senate process—surely a mockery of the notion of a trial. All this would be a purely domestic American affair, had it not been for the fact that in between his impeachment and his trial, Mr. Trump ordered the assassination of a top Iranian general in a drone strike in Iraq. Seeking to justify his decision, Mr. Trump merely spoke of an “imminent attack” and later seemed to conjure up a plot to bomb American embassies—a claim nobody else in the intelligence community or the US Defense Department has been able to confirm.