Can you posit a situation where the United States would ally with a country it is currently on unfriendly terms with?

“Politics makes strange bedfellows”

I was reading about the Pan American Union during World War II and noticed that the conference formalizing the union was held in Havana, Cuba. Cuba and the United States were allies. It got me thinking about how alliances have changed through our history, starting with the American Revolution.

Basically, pick a country that the United States is on unfriendly terms with, currently, and propose a situation in which they would become allies.