T5 and foreign countries

Visiting what foreign countries makes it longer or harder to adjudicate a background for a T5?

Just a visit? I think maybe Iran, Syria, Yemen, North Korea, other garden spots like that.

China or Russia might raise some eyebrows but not like the first few examples I gave. Before COVID a lot of people visited China.

Now, if you’re not just talking about a tourist trip but something longer term, especially if you were working there, then the list would probably get longer.