I've seen some sources that claim the ATACMS missiles have been in use for some time, and furthermore Russia can shoot most of them down anyway, so this is not really anything new.
The counter point is that the ATACMS missiles require US satellite guidance, and are now being used against targets inside Russia. However, again, some say even these attacks into Russia have already been happening for some time, so there's little or no actual change here.
The fact that this is being trotted around by the MSM makes it seem like the intent is to provoke Russia and try to stir things up before Trump gets in. However, if they do nothing more than they have already been doing, then Putin will probably just wait for Trump, rather than letting himself be goaded into an escalation he doesn't want. He's on a winning track in Ukraine, so why mess it up?