These countries have updated their advice for travel to the US

• A number of European countries along with Canada updated their US travel advisories this month.
• They cited stricter US immigration and gender rules after several travelers were detained.
• Data shows Trump's trade war is hitting travel to the US.

A growing number of countries have recently issued advisories for travel to the US, citing stricter immigration enforcement and changes to transgender rights after reports of foreign travelers being detained by immigration authorities.

Here's how Canada and European countries have updated their travel guidance.

Canada: registration rule for long stays

Canada warned citizens staying in the US for more than 30 days to register with the US government, following reports of a Canadian detained by ICE for two weeks.

A Department of Homeland Security rule, effective April 11, makes registration mandatory.

"Failure to comply with the registration requirement could result in penalties, fines, and misdemeanor prosecution," the advisory said.

Europe highlights gender rules and entry risks

Denmark, Finland, France, Ireland, the Netherlands, and Norway have all issued warnings about new US policies affecting transgender travelers.

In January, President Donald Trump signed an executive order recognizing only two sexes — male and female — prompting countries to update their travel advisories.

Denmark's March 20 update advised those with an "X" gender marker in their passports to contact the US Embassy before travel.

Finland's advisory, updated Tuesday, advises applicants to put their gender at birth. "If the applicant's recorded gender differs from their birth sex, US authorities may deny entry."

It also cautions that overstaying or misrepresenting a stay's purpose could lead to arrest or deportation.

France's Monday update urges travelers to ensure their visas reflect their sex assigned at birth and to check with the US Embassy and airlines for policy changes.

Ireland's advisory, also updated Monday, notes that those with an "X" marker or a passport gender differing from sex at birth should contact the US Embassy in Dublin.

The Netherlands' foreign ministry, meanwhile, advises that US visa applications only accept "M" or "F" as gender markers.

Norway's Monday update says that holding a visa doesn't guarantee entry, as immigration officers have final discretion. It also states that the US "only recognizes an applicant's gender at birth."

Germany and the UK: risk of detention

Germany's advisory warns that a US visa or entry waiver doesn't guarantee admission. "Criminal records, false information, or even slight visa overstays can lead to arrest, detention, and deportation," it says, following reports of three Germans held and interrogated for weeks.

The UK's Foreign Ministry issued a similar warning after a British traveler was denied entry at the US-Canada border and held in a US ICE processing center for 19 days. "The US strictly enforces entry rules," the advisory says. "Failure to comply may result in arrest or detention."

Travel impact

Figures suggest the Trump administration's policies and tariffs are dissuading travel to the US.

Statistics Canada data released earlier this month shows the number of Canadians driving to the US fell 23% in February compared with the same month last year.

Meanwhile, travel data firm OAG said airline bookings between Canada and the US are down 70% compared with last year.

Tourism Economics forecast a 15% drop in the number of visits from Canada this year, costing up to $64 billion in lost spending.

Adam Sacks, the consultancy's president, cited President Donald Trump's tariffs, "imperialistic" rhetoric, and reports of foreign travelers being detained by US immigration officials as "significant hurdles for the US travel industry."