I was wondering if you can churn Non US Amex products like HK Amex CX which has a 75k bonus. What would happen if you applied and got approved for a Non US Amex card to your US Amex cards?

For example do US Amex and Non US Amex talk to each other so to speak? Does anyone know of repercussions to one's US Amex cards if one applies and gets approved for a Non US Amex card? Do they shut down one side for example or are the completely separate and the left hand does not know what the right hand is doing?