Trump gives away the game in every post. The operative words are "Democrat run cities". Crime is the excuse for military control of civilian citizens he sees as enemies. There is a kernal of truth to the crime part, but grossly overstated and the trend is already toward lower crime in the stated cities.
But if it were really about crime, Memphis, St. Louis, Birmingham, etc would be at the top of the list for National Guard takeover. Imagine the maga meltdown if Biden had sent troops to one of those cities against the will of republican governors and local officials to "fight crime".