"Remember a couple of years ago, when [President] Trump first got into office, we were all so nervous that Donald Trump was some sort of sleeper agent who was going to sell America out to a foreign power behind our backs?" Stephen Colbert asked on Thursday's Late Show. "Well, it's Throwback Thursday!" He ran through the outline of the whistleblower complaint that over the summer, Trump made a very troubling "promise" to an unknown "foreign leader." Colbert saw the silver lining: "Thank God Trump never keeps his promises.""Trump denies he did anything wrong," Colbert said, reading the tweet. "Very good point: What kind of moron would think you would make an inappropriate offer to a foreign country while you were being recorded?" He let Trump answer that, then played a game to try and figure out what Trump promised to which leader. But it turns out, according to The New York Times, that the complaint actually involves a "series of actions" Trump took. "Oh, a series?" Colbert said. "Great. Now we can binge-watch the end of America."This story is "stunning," Late Night's Seth Meyers said. "Now, we don't know which foreign leader this is, and this is a complicated story, so just to help you follow along, we put together a helpful little mnemonic device. Remember: It's a [P]romise from the [U]nited States made by [T]rump to an [I]nternational leader, but we do not know their [N]ame. Could be anyone." (It actually appears to be somebody in Ukraine.)Meyers also answered Trump's question about whether he would say something "inappropriate" to a foreign leader over the phone: "It's not that we're dumb enough to believe it, it's that we're smart enough to believe you're dumb enough to do it." Still, Trump "probably feels like he has impunity to do whatever he wants because so far he's face almost no consequences," he said, making his case for impeachment. Watch below.