According to the official US Embassy website,
Ciudad Juarez
Guadalajara
Hermosillo
Matamoros
Merida
Monterrey
Nogales
Nuevo Laredo
Puerto Vallarta
Tijuana
VPP El Bajio
VPP Chiapas-Tabasco
You mean troops? None, besides those that are guarding embassies and consulates.
Mexico has numerous embassies and consulates around the world. Currently there are consulates in 26 states in the U.S.A. and in four provinces in Canada.
You should go to the American Embassy in Mexico (Mexico City) or any of the consulates in Ciudad Juarez, Guadalajara, Hermosillo, Matamoros, Merida, Monterrey, Nogales, Nuevo Laredo, Puerto Vallarta or Tijuana.
Department of State
Urban legend, actually. There are no Chinese troops stationed in Mexico, besides those guarding Chinese embassies and consulates.
Department of State
Department of stateDepartment of State
There are 73 Mexican embassies around the world, with many more consulates and diplomatic delegations in countries such as Canada, Argentina, Spain, Germany, the Russian Federation, China, Japan or Australia.
The Department of State, as the embassies and consulates (http://www.usembassy.gov/) from the US depend upon that government agency.
If you and your children have a passport, just get on a bus or plane and go; otherwise you should contact the American embassy or any of the consulates on major Mexican cities for legal advice.
Consulates of the Orange Free State was created in 1855.
Consulates of the Orange Free State ended in 1902.