Hi everyone. I'm thinking of applying to MA in International policy/International relations in a couple of top-tier universities in the US. Problem is, I already have a master's degree in a somewhat related field from a university in my home country. Here I got MA in what is literally translated as "Foreign Regional Science". The curriculum was practically politics/political economy/international relations/globalization but mostly concentrated on Asia-Pacific hence "Regional Science".
Do you think this fact (already having a related MA) can be a potential red flag for people who will review my application?

Hi. I think it might be. I assume that you have to write a cover letter showing your motivation. If your motivation is getting an MA from a top university, you can write this. Otherwise it would sound unusual for the reviewers.

If ypu already have a Masters in this field, why would you get another one?
If your reason is to get a "top" university on your CV, this would absolutely crazy.
If I was hiring you and that was your reason, your interview would be over pretty quickly because it would tell me that your main focus was not on your research but on meaningless sideshow trivialities.

Go for it!

In the interview/application, make sure it is the topic that interests you and say how this MA differs from your previous masters. Second degrees in unrelated fields are okay, so you just got to sell them on how they are unrelated. It is problem but not a massive one.

I have seen a few people like you, who are effectively doing a second degree in the UK because no-one recognizes the degree from their home country. And universities take you because you are paying fees.