Protection against lawsuits through non-US company

The decisive factor for infringement is the country (and the patents that is pending in that country) where the infringing acts have taken place. Whether or not the infringer is a local company or a foreign entity is not relevantL a Mexican company can infringe a patent in the USA and a US company may infringe a patent in Mexico.
The lawsuit may be brought to the infringer by the (legal) person who owns or has been assigned the patent right. This also does not necessarily have to be a local entity. Again: a Mexican company, owning a US patent, may start infringement actions against a Canadian company if that company would infringe in the territory of the USA.