system
Given the following post, respond as if you're commenting on Reddit:
human
[The Purge] What would foreign relations and world opinion be of America as a result of the yearly purges?
gpt
Most of the world would keep doing business... on the conditions that A) their embassies and consulate offices are on the list of "no-go" government facilities and B) their citizens could seek protection if needed.

Foreign travelers would be able to take refuge in their respective embassies (as well as the facilities of friendly nations, due to mutual support agreements), and would be among the few groups able to present themselves to a police station or military facility seeking sanctuary. For those too far out in the sticks to get to a proper facility, or who wait too long to seek shelter and get caught out during the event, the last resort is being temporarily named a consular officer, sent a PDF file so they can print out appropriate signage and take their best chances hiding out at home.

An individual foreigner caught out on the street is as much fair game as anyone else. 

As far as participating in the Purge, yes, they do. In a situation comparable to American sex tourism, foreigners who come over to Purge aren't breaking any American laws during Purge Night, but are still beholden to their home governments; if they get caught on camera engaging in violent crime, they may find a trial waiting for them back home. For nations that don't approve of the Purge, travel plans for the States that overlap Purge Night tend to be heavily scrutinized, and questions will be asked if the individual didn't check in with an embassy or consulate before the start of "festivities". 

Nations that approve of or are neutral towards the Purge would be less rigorous, and travel agencies in those nations might go as far as advertising Purge travel as a form of adventure or extreme sport, either as observer ("Sit safely atop the embassy and watch the fireworks") or participant ("All overseas guests will receive a briefcase containing a mask and a weapon. Please consult the price list below for weapon options.")