Let’s look for a moment at Cuba, which seems like it might well be next on the Trump hit list. The president said yesterday that he was looking for a “friendly takeover” of the island nation, and it’s clear that the tool he’s using is energy: after cutting off Venezuelan supplies, he’s also pressured Mexico to stop sending crude to Havana. As a result, he explained, “They have no money. They have no anything right now.”

As it happens, I went to Cuba to do some reporting the last time the country was in such a fix, following the collapse of the Soviet Union and with it Havana’s economic lifeline. In those days the country’s biggest problem was food, and it survived in part with a fairly remarkable turn towards urban agriculture. I was endlessly impressed with the Cubans I met who were learning how to grow the food their neighbors needed, even as I was depressed by the police state they were inhabiting.

Now the overwhelming problem is energy, and it’s here that something else quite profound has been happening: an almost unbelievable surge in the production of solar power.