They do come with a 1- year warranty by Sony. I don't think it would be bound by borders.
If I may make an observation. I bought these because Sony has a brilliant ad campaign for these and the over the ear model. I immediately missed the sound of my Sennheisers. I first got the wired Momentum model and fell in love. The very first time I heard them, my jaw literally dropped open. I listen to every genre and they sound amazing with every one. It was as if I was hearing every song I played for the first time. Sound, just as beauty is a personal thing. I've owned almost every brand made and these have a sound like no other and they work fantastically well, as far as connecting effortlessly through Bluetooth.
In a perfect world, these would offer every feature that the Sony has. I do miss the total noise canceling, but I would rather hear a few outside sounds and have a superior sound. Give these a try. I don't think you'll be disappointed.