Lew Lukens, the highest-ranking U.S. official in London, is a piece of work.  The Chargé d'Affaires, or acting U.S. ambassador to the United Kingdom, undercut President Trump's criticism of London's Mayor Sadiq Khan in the wake of the recent terror attack by brazenly tweeting high praise to the leftist leader, whose hostility to Trump is well known. Lukens's tweet, spotted as a retweet on former Obama deputy national security adviser Ben Rhodes's Twitter feed, reads: I commend the strong leadership of the @MayorofLondon as he leads the city forward after this heinous attack. – LLukens 3/3 https://t.co/p4dDZuCpyO — U.S. Embassy London (@USAinUK) June 4,...