PARIS — The German government of Chancellor Angela Merkel falls, torn apart by demands from her conservative interior minister, Horst Seehofer, that refugees already registered in another European Union state be thrown out of Germany.

The xenophobic Alternative for Germany, or AfD, enters a new nationalist governing coalition. The party’s cry of “take back our country and our Volk!” echoes through Berlin.

Congratulatory calls pour in from the nationalist leaders of Hungary, the Czech Republic, Poland, Italy, Austria — and the United States. The American ambassador to Germany tweets his approval.

European Union leaders, buckling before the anti-immigrant tide, opt for the establishment of large detention centers for all migrants. Asylum seekers whose claims are verified will be admitted, while economic migrants merely in search of a better future will be evicted.