Because of his many years of experience in the Middle East, Petraeus is also the right choice to try to untangle the greatest foreign policy problem the Trump administration will inherit, which is the Syrian civil war.

In an interview in June, Petraeus told me that Syria is like “Chernobyl … spewing radioactive effects everywhere — violence, instability, extremism and the tsunami of refugees into the countries of our NATO allies and European partners, causing the biggest challenge in Europe in many decades.”

In the June interview, Petraeus was clear-eyed about how tricky ending the Syrian civil war is likely to be, saying, “It’s gotten more and more and more difficult, obviously, as the opposition forces have fragmented, have atomized, as the Islamic State has stood up, as the al Qaeda affiliate has been established, as the Iranian Revolutionary Guard Quds Forces advisers began helping [Syrian dictator] Bashar al-Assad — and then Lebanese Hezbollah fighters, then some Iranian forces and Shia militias, then Russian air support and special forces. This has just gotten diabolically more difficult.”

When Petraeus was CIA director from 2011 to 2012, he dealt with many of the key national security issues likely to take center stage in the Trump presidency, from North Korea to combating jihadist groups. It was when he was director of the CIA that Petraeus urged the arming of the Syrian moderate opposition, which was overruled by President Obama. Historians may record this as a missed opportunity to help blunt the rise of the group that became ISIS.