A growing number or countries have issued travel warnings to the USA. Some travellers opting to boycott it entirely including not buying American products and services. Stricter border enforcement has recently led to the detention of tourists and an increasing number of foreign visitors facing challenges as a visa or entry waiver does not guarantee entry and you may be detained.
The list of countries who have issued travel warnings for travel to the United States include Austria, Belgium, Canada, China, Denmark, Finland, France, Germany, Ireland, Netherlands, Norway, Portugal, Slovakia, Slovenia, United Kingdom.