No, but that hasn't stopped people from framing it that way.
A Mexican helicopter crossed into Arizona on Thursday and fired two shots at U.S. border agents, according to the U.S. Border Patrol. The helicopter crossed about 100 yards past the border and the incident took place at the Tohono O'odham Indian Nation reservation.
Mexico said the helicopter was tracking smugglers at the border and was shot at by criminals. What happened next is still under investigation, with one Mexican spokesman saying the helicopter never crossed over.
"They could say they didn't fire at the agents intentionally," Art del Cueto, president of the local border patrol union, told the AP. "But for them to say that they were no shots fired within the United States, toward the United States Border Patrol, is a lie. They got in contact with our managers and apologized for the incident."
Similar situations: This isn't the first time Mexico's military has crossed the border and caused a stir in the U.S. In January, two heavily armed Mexican soldiers in camouflage crossed into Arizona, where they were met by border patrol agents. Both sides drew guns, creating a standoff.
The soldiers claimed to be pursuing smugglers, and the standoff lasted for 35 minutes, though no one ever fired and the situation was defused peacefully. Mexico maintained that the pair must have been smugglers wearing military uniforms, but eventually confirmed they were soldiers after a U.S. investigation.
In 2011, more than 30 Mexican soldiers in Humvees crossed the Rio Grande into Texas. The "accidental invasion" occurred when the team crossed a bridge without realizing the only way to turn back was to go over U.S. soil.
More cooperation: Despite your Facebook friends (you know the ones) calling it an act of war, officials are using the situation as an example of why the U.S. and Mexico actually need to work together more closely.
Tensions at the border have risen as migrants, especially young ones, cross over; thousands of children from Mexico and Central America cross into the U.S., which can make for further mishaps if Mexico and the U.S. can't cooperate. "It's becoming more than normal," domestic security professor James Phelps told the Los Angeles Times, saying in the past accidental border crossings only happened once every two or four years.
So no, Mexico did not just invade the U.S. and the U.S. is certainly not going to invade Mexico back. As for what led to the potentially (but luckily not) deadly mix-up, the FBI and Mexican agencies are still investigating.