Countries have spied on each other forever, and any country that doesn't engage in such activities is run by fools. No, the Us would not go to war over another country spying on us, it would just expel the spies, though in an earlier era it might have shot them. We Europeans spy as much as anyone, and always have.

Espionage is an organizational reality. To pretend you don't have to care about such things is like being a tourist that wanders into the bad part of town flashing money everywhere and then expresses astonishment if their pocket is picked or they are otherwise taken advantage of.