For international experience to be significant it has to be something that you can write about at length and appropriately in a b-school essay.

Can you articulate how you lead a team in a multi-national or cross border environment? This is what the adcom would want to see if you were writing an essay. A lot of applicants have worked occasionally overseas. More important is what you learned, how it changed your perspective, how you overcame an obstacle and how you produced a positive team outcome.
That is, what you got out of it and what you can put down on paper is what will set your experience apart from other applicants. That is where I consider the line drawn with respect to whether or not an experience is significant.
With respect to any extracurricular international experience (start-up, professional volunteerism, etc.), if you can write about it effectively as part of your positioning then it's significant and should be considered for an essay topic. So yes, this could fall under international experience as you interacted with others with perhaps different operating norms and value sets.
Remember, I always tell my clients "WWACD" or "What Would the Adcom Do?" Keeping that perspective help put a reality check on a lot of questions that pop up during the admissions process.

If you are interested in a free initial consultation, please email mba@amerasiaconsulting.com. Our boutique approach pairs you with a consultant capable of walking you through the above steps and perfecting your application.

If you would like to gain immediate insight into our school specific expertise and MBA program analysis, make sure to download our free How to Apply > guides.