The US government set the precedent that governments can legally hack foreign computers
"Speaking at a press conference on Wednesday, Trump said: "Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing. I think you will probably be rewarded mightily by our press."
I personally have little doubt that Israelis, French, Germans, Brazilians, Mexicans and Iranians have also hacked into US government computers, and that at least the Israelis, French, Germans had success.
>> So Trump is merely asking the Russians to look at their copy of the emails that have since been deleted from US government and Clinton personal mail servers, copies they made back before the emails and backups were deleted.
It would be pointless to ask them to hack in and find the emails on US government servers now, they're all deleted from US government and Clinton private email servers. <<
Now, the USA has publicly stated that federal agencies can legally break into foreign computer systems, including foreign government computer systems, and the intelligence services of other countries are all federal agencies, and to them US computer systems are all foreign computer systems.
The USA has set the precedent that it is legal.
Nobody at the NSA went to jail. The US does not consider it a criminal act for one government to hack into another government's computer systems. Rather, when discovered it is just a case for diplomatic tit-for-tat gestures.