According to “sources with knowledge” talking to CNN—whatever that means—Michael Cohen is prepared to tell Special Counsel Robert Mueller that Donald Trump knew in advance about the June 9, 2016 Trump Tower meeting between Don Jr. and Russians. The president still denies knowing about that meeting beforehand. Don Jr. was emailed by a British music promoter, Rob Goldstone, who promised that the Russian “crown prosecutor” had information that would “incriminate Hillary and her dealings with Russia.” When the meeting took place, in walked two Russian nationals, Rinat Akhmetshin and Natalia Veselnitskaya, who proceeded to talk to Don Jr., Jared Kushner,...