Can international flights by a US operator be performed paperless or do you need complete paper charts?
With virtually every major US air carrier today using EFB's, the use of paper charts in the flight deck has largely fallen to the wayside. Flight crews are still being provided with the exact same information, only now it is in digital form. Most, if not all US air carriers use navigational charts and plates published by Jeppesen. Unlike FAA NACO charts and plates, Jeppesen publishes charts for airports all across the world in a greatly standardized form. This allows information to generally remain similar across countries and helps to reduce some of the differences pilots operating international flights would otherwise face. Whether paper or digital, US based flight crews would likely receive charts from Jeppesen.
All of the EFB apps in use by airlines are designed to automatically provide pilots with current charts and plates needed for any given flight in the carrier's network, provided the area is covered in the chart subscription. Prior to operating an international flight, an airline (likely their dispatch department) will review their chart subscription package to ensure charts/plates are included to cover the routing, destination, and alternate(s) of any international flight. Any areas needed that are not currently included in their subscription would be added. Once added to the airline's subscription, the charts would then automatically populate to the EFBs issued to pilots. Pilots would then just need to make sure the new charts were downloaded and they would be good to go. Pilots would then be receiving the exact same information digitally that they would if they had been provided paper charts.
From a regulatory perspective, the FAA, EASA, and ICAO have all developed standards for EFBs and as a result pretty much all developed countries allow their use. As long as an airline has received the appropriate approvals and meets standards, the use of EFBs should be a non-issue. In the US, FAA EFB standards meet or exceed ICAO standards, and ICAO standards would likely be the minimum requirement while operating internationally. I am not currently aware of any country that disallows the use of EFBs for charts, but should such a scenario arise, then an airline could potentially be forced to use paper charts. However, the odds of that happening are slim to none.
I know of at least one Part 121 carrier that routinely flies internationally with no requirement for full paper charts, and beyond the approvals for the EFB's as a replacement for paper charts in general, I don't know of any special approval needed to go without them internationally.
We do have paper High enroute charts for international (but not domestic) airways; I can't find a reference if those are required or not (and if so, by whom: FAA, other countries, or our company).
It's always hard to prove a negative, but I suspect that if your operation is approved to go EFB-only, then that approval isn't limited to only domestic routes. There may be some country that requires everybody to have the paper charts, but I don't know who.
Overwater ops has its own rules; for that, a paper plotting chart may well be required even with EFB's for enroute & terminal reference.