Years after defeating the Islamic State on the battlefield, world governments are now grappling with what to do with the thousands of war-related detainees in Syria.

A year after Russia’s invasion, Ukraine is suffering a catastrophic humanitarian crisis. The outflow of millions of refugees has placed a strain on neighboring countries.

The European Union and the United Kingdom came to a last-minute trade deal on Christmas Eve, narrowly averting the hardest of all potential Brexits. But major uncertainty remains.

The United Kingdom and European Union are engaged in another bout of Brexit brinkmanship, with Prime Minister Boris Johnson pushing a bill that would undo their previous agreement. Here’s what to kno…