When that actually happens, we can discuss it.
Right now we are discussing DC, and two things are definitely true:
1) Crime has been a problem there forever, and for some reason we have always been conditioned to just accept that as normal.
2) Trump has the authority to take action, since it's a federally-controlled city with no states rights.
Therefore, I can't understand the objection here. It's important to send a message to the DC local government that they aren't really in charge, and they need to clean up the crime situation or it will be done for them.
The matter of the other cities is more complicated. Simply sending in federal troops to regular cities such as NY and Chicago can be a violation of states' rights, provided that the state government objects to it (which in those cases, I'm sure they will). It is still justified during times of clear civil unrest (such as what occurred in LA recently), but it isn't really justified for just normal high crime. However, if the crime is impacting federal areas, it is justified to send troops to protect those buildings and areas if needed.
For those yelling "omg fascism" to the DC action, were you saying the same thing when your rights were nonsensically removed during the 2020-21 COVID era? Did you oppose censorship of "misinformation", which was a big thing on the left (and openly supported by Biden)? If not, you're a hypocrite.