BERLIN - Several European countries have updated their travel advisories for the United States this week following the detention of multiple European nationals, including German citizens, upon arrival.

Germany's Foreign Office said it is taking the recent incidents involving German travelers seriously.

"We have clarified and now clearly emphasize that an Electronic System for Travel Authorization (ESTA) approval or a US visa does not, in every case, authorize entry into the United States," a spokesperson told public broadcaster ARD's Tagesschau.

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The advisory update follows reports of three German nationals being detained at US entry points, including one green card holder. Two of the individuals have since returned to Germany.

In response to the incidents, Britain also revised its travel advice, warning of strict enforcement of US immigration laws. "You may be liable to arrest or detention if you break the rules," the Foreign, Commonwealth and Development Office said on Thursday.

Britain's foreign office confirmed earlier this month that it was providing support to a British national reportedly detained at the border in the United States, according to Reuters.

Finland issued a similar update on Friday, cautioning that even valid travel documents might not guarantee entry under current US policies. The Finnish Foreign Ministry also noted recent changes requiring visa or ESTA applicants to declare both their gender and gender at birth, which could result in denied entry if inconsistencies are found.

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Additionally, Finnish authorities warned travelers to avoid large gatherings in major US cities, citing the risk of politically motivated demonstrations turning violent.

According to Finnish broadcaster Yle, the tightened advisories reflect evolving US immigration policy under President Donald Trump's new term.