What is Julian Castro's concern about the use of drones over Mexico?

Julian Castro expresses concern about the potential offensive use of drones over Mexico, particularly regarding fentanyl labs. Through a thought experiment, he illustrates the dangers of this approach by reversing the scenario: what if Mexico flew drones over Texas to target illegal weapons and killed US civilians in an offensive strike? He highlights that such actions would create severe diplomatic problems between the United States and Mexico, especially with Trump potentially returning to office. Castro fears that authorizing offensive drone operations could establish a dangerous precedent that might escalate tensions and lead to unintended consequences if political leadership changes or makes impulsive decisions.