The memo

The memo situation explained ...

Back in 2013, an American, Carter Page (who would later join the Trump campaign in 2016 as a foreign policy advisor), was found, through FBI surveillance of Russian agents operating in New York, to be cooperating with those Russians (Russian Spies Tried to Recruit Carter Page Before He Advised Trump - The New York Times). The FBI interviewed Page in June 2013 about this.

Later, on Oct. 19, 2016, the FBI obtained a FISA warrant to surveil Page about a month *after* he had resigned from the Trump campaign because of his numerous ties to Russia. Every 90 days the warrant had to be signed off on to continue the surveillance, and eventually, by 2017, Rod Rosenstein was the one who did the signing.

Now, Devin Nunes and the White House have crafted a memo that falsely alleges that Rosenstein (a Republican, BTW) and the FBI are allied against Trump and have based their FISA warrant application on information from the Steele dossier. This is not true - Page had been a person of interest to the FBI since 2013.

By making this false claim, Trump believes he can discredit the whole Russia investigation, or at least fire Rosentstain, putting in his own puppet to oversee the investigation, a puppet who will either fire Robert Mueller (another Republican) and end the Russia investigation, or more insidiously, he will strangle the investigation by controlling Mueller's options and actions.

Read more: The 9 biggest questions about the Nunes memo, answered