I thought if you buy applecare it was covered internationally? At first it was just on macs but I thought they extended it to iPhone's as well.
I had Applecare + on my iPad 3 that I purchased while I was working in New York, had it replaced under the 1st year's warranty no issues.
My phone didn't have AC+, but was still replaced under the year's warranty in the UK.
I can't find it now, but there's an Apple document somewhere that basically says "mobile" devices have international warranty (so iPhones, iPads, laptops & iPods) are covered internationally.
Watch does not use cellular technology this shouldn't be an issue with that. Not everyone is tech savvy out there and there are instances when someone has to make an appointment at the Genius Bar even for a minor thing that could be resolved by the user. I've seen it on several occasions with other people at the Genius Bar.