I believe the accounts for shipping he is using have been flagged in western countries at this point, it's not complicated to intercept packages via a flag warning in a computer system once the ID associated with a package gets scanned, get a beep then open contents & examine; if there's a message on the system to contact LE & they know what they're looking for it doesn't take much to figure it out.
All started most likely with one of the US alphabet agencies passing the info' on to other "allied" countries intelligence agencies. Fucking bastards.