As the Trump Administration continues its aggressive stance on illegal immigrants, tourists are finding themselves caught in the dragnet. Legitimate travelers from other countries are increasingly being denied entry to the country for what some are politely describing as confusing reasons. Others have even found themselves taken into custody and placed into detention for weeks at a time.
This has led to more countries advising their citizens to make sure everything is in check before traveling to the United States, which doesn't seem completely unreasonable at first glance. When making plans to travel anywhere, the onus is on the traveler to make sure they have the proper identification, documentation, and visas in place before leaving on the trip. Unfortunately, that has become increasingly difficult with the United States.
New rules and regulations seem to be put into place quickly and haphazardly, leading to more and more confusion at border crossings. This has led Canada, France, the United Kingdom, Finland, Germany, and Denmark to issue warnings to their citizens about travel to the United States. A major potential issue for anyone from countries that allow gender markers beyond male and female on their passports. The US has changed that rule, meaning anyone with any type of nonbinary marker could have problems getting in.
The reality is that every country has the final say on who does and doesn't cross their borders, and are not necessarily obligated to provide a reason or an explanation if entry is denied. While these countries are not advising against travel to the United States yet, their governments are saying that you need to be especially careful when entering America. Any question about your passport or paperwork could potentially lead to being detained by ICE.