U.S. to be sued for...defending its borders?

From the Houston Chronicle:

Mexico warned Tuesday that it would file lawsuits in U.S. courts if National Guard troops detain migrants on the border, and some officials said they fear the crackdown will force illegal crossers into more perilous areas to avoid detection.
...
"If we see the National Guard starting to directly participate in detaining people ... we would immediately start filing lawsuits through our consulates," Foreign Secretary Luis Ernesto Derbez told a Mexico City radio station.

Rumor has it that one such "more perilous area" is MEXICO! Can you imagine if Mexicans had to stay in Mexico, forced to apply for legal entry into the U.S.? Why, just what would this world be coming to?

Is a foreign country given access to OUR courts to sue US for anything, much less protecting the sovereignty of OUR country? Given how liberals get erections over the idea of al Qaeda terrorists getting access to lawyers, I have little doubt they would support a foreign country suing the evil U.S. for having the temerity to secure its borders.