My understanding is only if they request it.
Special Forces could get the Colombian Mafias on the run in Mexico, they have nowhere to go and could be cornered.
The CIA has a full picture of who is who and the network of the narco terrorists in every Mexican State.
Because the Mexican Federal Government can only govern effectively Mexico City (24 million people), US Special Forces could be especially effective in all other states where the narcos control.
The narcos control the political strings in the states outside Mexico City, they have bought the politicians there or have neutered them through a series of murders and other terrorist acts.
So most enforcement actions by local law enforcement is minimal because the Chiefs of Police are neutered or paid off by the narcos. The Mexican federal government has sent their own special forces from Mexico City to other states to fight narcos with some success but the action falls far short of victory.
It is said that Mexico City is off limits to the narcos because that is where the heads of the narco families live, where their children go to school.
But US Special Forces equipped with real time CIA intelligence could exterminate the upper ranks of all the narco families in a matter of weeks.
The problem is the Mexican political establishment is not ready to permit US Special Forces to operate inside their jurisdiction unless it is so secret that no one would know they were ever there.
And they likely never will be. Which means Perry was either blowing smoke or he would do so w/o their approval.