WASHINGTON The Justice Department special counsel has evidence that Donald Trump’s personal lawyer and confidant, Michael Cohen, secretly made a late-summer trip to Prague during the 2016 presidential campaign, according to two sources familiar with the matter. Confirmation of the trip would lend credence to a retired British spy’s report that Cohen strategized there with a powerful Kremlin figure about Russian meddling in the U.S. election. It would also be one of the most significant developments thus far in Special Counsel Robert Mueller’s investigation of whether the Trump campaign and the Kremlin worked together to help Trump win the White...