Answer: First, let's keep in mind that your firm will not – and should not – know that you are thinking about making a move. Only after you have accepted an offer, all of your references have been checked and you have been given a start date, can you even think of giving notice to your current employer.
It is unfortunate that you feel you need to make a move since you have characterized your relationship with your current employer as being a good one. Are you absolutely positive that you cannot get more international work at your firm? Have you spoken to anyone about this issue?
The other issue I need to point out to you is that you are a first-year associate and I hate to see you make a move so early in your career. Is there any way you can stay at your current firm for at least one more year? By the way, as a first-year attorney the opportunities available for you are not going to be as plentiful as they might be in a year or two from now.