> but for some other parts of the world (esp. east/SE Asia), US special forces are going to be instantly recognizable as foreigners because they generally don't look anything like the locals.
Not everyone in the United States is a blond haired, blue eyed white person.
Also, simply adopting the local dress is often enough in many countries where immigration has been a thing for decades now. You also can adopt local hair styles, this is why you'll see a lot of the special forces community with long hair and beards in Afghanistan and similar countries.
If you dress the part, walk the part, speak the part (the DLIFLC alone teaches 24 languages) you can blend in to a city pretty easily. Will you stand out like a sore thumb in a remote village, almost certainly, can you stroll through a town of tens of thousands of people with very little attention paid to you, usually.
With previous U.S. actions though it is usually go into a country mostly-overtly and just train local fighters (or fly them to the United States for training) but the Special Forces community has many instances of infiltration in advance of regular military units, as well as ongoing humanitarian efforts (which helps build awareness of local cultures and customs and dialects). Green Beret medics for example have been used in multiple African countries to provide medical aid, just doing general health checkups on villages and the like, a buddy of mine that was an 18D (Army - special forces medical sergeant) mentions it in his book Love Me When I'm Gone (by Robert Patrick Lewis) as well as a lot of training with foreign military in their country, in his case Germans.
---
Say the Asian country of Makebeleivia wanted to get special forces in place into a country that was largely caucasian prior to a proper attack to disrupt. How do they do it? You send some people in as tourists on various commercial flights, you can use multi-national companies you control or have some coercion over to bring workers over on work visas (and might actually do work for weeks or months), you get some in on student visas, you can pay coyotes to sneak some in, you can sneak some in yourself if there is a coast by deploying them via submarine and having them slip into tourist towns as tourists or with fake identification. Then you use any number of means to arm them with conventional firearms and if you want to cause mayhem you have your demolitions experts cook up crude explosives. The purpose here would be to create panic and tie up first responders, this also puts the national government agencies on edge thinking there is some sort of terrorist attack and is more likely to distract than make them think "oh hey a military invasion might be underway". You can either go after relatively 'usless' targets like crowded public places or you can go after more strategic targets like damns, ill-protected power plants, substations, key bridges in and out of large cities or bridges that create strategic issues for moving heavy equipment, etc.
---
A somewhat good example of foreign agents operating on foreign soil, although in a different capacity, is Mossad. They've done a lot of kidnappings on foreign soil to bring war criminals back to stand trial, assassinations abroad, kidnapping defectors to stand trial, etc
Find some examples here https://en.wikipedia.org/wiki/Operations_conducted_by_the_Mo...
One of the more high profile things Mossad has done is going after Black September, for the Munich bombings. The 2005 film Munich is about this.
Also, Sayeret Matkal, which is basically Israeli's Delta Force - they've sabotaged airliners, done kidnappings and raids, assassinations, done physical evidence gathering in Syria.