Over the past few weeks, National Security Adviser H.R. McMaster has pushed out a handful of National Security Council officials who were holdovers from his predecessor, Michael Flynn, and seen as allied with White House chief strategist Stephen Bannon and his nationalist wing of the Trump administration. The house cleaning started with Rich Higgins, the NSC director of strategic planning and the author of a seven-page memo titled "POTUS & Political Warfare" that was being passed around among likeminded members of President Trump's campaign and transition. When the memo, written in May, was found on Higgins' computer in mid-July, he was told by McMaster's deputy that he could resign or be fired, sources tell Foreign Policy, which published the memo on Thursday.

The memo lays out what Higgins views as the concerted effort to thwart and topple Trump. "While opposition to President Trump manifests itself through political warfare memes centered on cultural Marxist narratives, this hardly means that opposition is limited to Marxists as conventionally understood," he wrote. "Having become the dominant cultural meme, some benefit from it while others are captured by it; including 'deep state' actors, globalists, bankers, Islamists, and establishment Republicans."

Foreign Policy's Trump administration and NSC sources say McMaster discovered the memo during a hunt for internal leakers to right-wing blogger Mike Cernovich, who has been agitating to get McMaster fired for months — a campaign that has picked up since McMaster fired the four Flynn holdovers. Foreign Policy explains what happened next:

In the meantime, however, the memo had been working its way through the Trump White House. Among those who received the memo, according to two sources, was Donald Trump Jr. Trump Jr., at that time in the glare of media scrutiny around his meeting with a Russian lawyer at Trump Tower during the presidential campaign, gave the memo to his father, who gushed over it, according to sources. In a comedy of errors, Trump later learned from Sean Hannity, the Fox News host and close friend of the president, that the memo's author had been fired. Trump was "furious," the senior administration official said. "He is still furious." [Foreign Policy]

Several of the magazine's administration sources said they believe Higgins' analysis was correct, if sometimes a little conspiratorial, and that despite Trump's sticking up for McMaster, his job isn't very secure. You can read more, and read the memo, at Foreign Policy. Peter Weber