Why UK and Germany issued fresh travel advisory for those travelling to US?

The United Kingdom and Germany updated their travel advisories for the United States, warning citizens of strict enforcement of immigration rules after multiple cases of detentions at US entry points.
The move comes after three German nationals were denied entry and placed in detention, and reports of a British citizen facing a similar situation.
The UK foreign office issued its updated advisory on Thursday, cautioning British passport holders about the harsh consequences of violating US immigration laws. "The authorities in the US set and enforce entry rules strictly," the advisory stated. "You may be liable to arrest or detention if you break the rules."
The updated guidance now explicitly urges travellers to "comply with all entry, visa and other conditions of entry."
According to Reuters, the UK Foreign Office had earlier confirmed support for a British national detained in the US, following reports of a woman being held at the border.
Germany also revised its travel guidance this week after three of its citizens were detained when attempting to enter the US. "A criminal conviction in the United States, false information regarding the purpose of stay, or even a slight overstay of the visa upon entry or exit can lead to arrest, detention, and deportation," Germany’s Foreign Ministry stated.
The ministry clarified that possessing an Electronic System for Travel Authorization (ESTA) or a US visa does not guarantee entry, as US border authorities have the final say. "The final decision on whether a person can enter the United States rests with the American border authorities. But this is no surprise; it is the same in Germany," a ministry spokesperson told Der Spiegel.

The advisories come amid increasing reports of European nationals being denied entry and detained at US airports and border crossings. The Trump administration’s intensified crackdown on immigration has raised concerns among allied nations, as even visa holders and legal residents have faced difficulties entering the country.
Among those affected is Fabian Schmidt, a 34-year-old German green card holder who was detained in Boston and later transferred to a facility in Rhode Island. His mother, Astrid Senior, alleged in an interview that he was "violently interrogated", stripped naked, and forced into a cold shower by two officials.
Two other German nationals, Jessica Brösche, 29, and Lucas Sielaff, 25, were also detained and later deported. Brösche, who attempted to enter the US from Tijuana, Mexico, was held at Otay Mesa Detention Center for over six weeks. Friends claim she was placed in solitary confinement for nine days, though San Diego CoreCivic, which operates the facility, denied the allegation.
Sielaff, who entered the US on a tourist visa and later visited Mexico, was detained for two weeks before being sent back to Germany, his girlfriend told Tages-Anzeiger.
Germany's foreign ministry emphasised that the revised guidance does not constitute an official travel warning but serves to inform travellers of stricter enforcement measures.
Travellers from both countries are advised to consult their respective foreign offices and verify entry conditions before visiting the US.