These countries have issued advisories about travelling to the U.S.

Tourists have been stopped at U.S. borders and held in immigration detention centers for weeks.
Several European countries have issued travel warnings to their citizens, citing concerns about potential problems at the U.S. border due to the Trump administration’s policies.

Since taking office in January, U.S. President Donald Trump has issued executive orders tightening border policies, tightening visa processing and cracking down on illegal immigrants.

The tougher regulations have led to citizens of other countries being denied entry or being detained, including a Canadian. Vancouver-based entrepreneur Jazmine Mooney was held in several U.S. detention centers for nearly two weeks. She was arrested earlier this month while trying to get a visa at the U.S.-Mexico border and was given little information about why she was detained.

In another case, US border agents prevented a French space scientist from entering a conference on March 9 and deported him for writing “hateful” messages against US policies on his mobile phone.

United Kingdom
The British government has advised its citizens to comply with all entry requirements into the US. The country has warned that travelers who do not comply may be arrested or detained and has stressed that US entry rules are strictly enforced.

Germany
Germany has issued a travel advisory stating that having a visa or a visa waiver does not guarantee entry to the US. A German foreign ministry spokesman said the country had updated its travel advisory following the arrests of several German citizens at the border.

Denmark
Following Trump’s policies on transgender people, Denmark has advised its trans citizens to contact the country’s embassy in Copenhagen before travelling to the US.

Finland
Finland has issued a similar warning to Denmark about travel to the United States after Trump signed an executive order recognising only male and female.

Canada
The Canadian government updated its travel advisory for the United States on Friday. The advisory says Canadians and other foreign nationals staying in the US for more than 30 days must register with the US government.

Travelers are advised to visit the US Citizenship and Immigration Services website for more information.

The Canadian government also said that Canadian residents can check whether they are automatically registered by checking their I-94 form on the US Border Protection website.

“Failure to register could result in fines, fees and legal action,” the advisory says.

The Canadian government also stressed that the government cannot intervene if travelers fail to comply with entry or exit requirements.

US border officials may also ask Canadians for additional documentation, such as proof of residency, employment or study in Canada, and proof of financial ability to cover travel expenses.