"What I got from President Obama was a commitment to a full investigation... and if they turn out to be true to impose corresponding sanctions,"
Good luck with that "promise" being kept. After the investigation, the documents will be sealed under national security and the "sanctions" will be for the NSA to be less transparent in their activities. Like I would trust sanctions from a secret court that allows spying on foreigners.
"The U.S. Foreign Intelligence Surveillance Court of Review concluded on August 22, 2008, in the case In re Directives [redacted text] Pursuant to Section 105B of the Foreign Intelligence Surveillance Act that the "special-needs" doctrine applied by analogy to justify a foreign intelligence exception to the warrant requirement for surveillance undertaken for national security purposes and directed at a foreign power or an agent of a foreign power reasonably believed to be located outside the U.S."
Mexico is located outside of the US and thus for national security the exception would be applied.