Israel and Gaza. Yemen and the Red Sea. Lebanon, Syria, Iraq — and now Pakistan, too.

At every flashpoint in a set of conflicts spanning 1,800 miles and involving a hodgepodge of unpredictable armed actors and interests, there’s been a common thread: Iran. Tehran has left its imprint with its behind-the-scenes-backing of combatants in places like Lebanon and Yemen, and with this week’s direct missile strikes on targets in Iraq, Syria and Pakistan.

The Iran connection stems partly from Iran’s decades-long efforts to deter threats and undermine foes by building up like-minded militias across the Middle East.

In addition, Iran itself, like neighboring countries, faces armed separatist movements and terrorist groups in conflicts that readily spill over borders.

But what does Pakistan have to do with Gaza? Here’s a look at how Iran ties together recent tensions.

What’s the back story here?

Ever since the 1979 revolution that made Iran a Shiite Muslim theocracy, it has been isolated and has seen itself as besieged.