Politics is messy, and nowhere is it messier — or bloodier — than in the Middle East. The “Cradle of Civilization” often seems determined to become civilization’s tomb as well. Sunni and Shiite, Arab and Jew, native tribes and former colonial powers — from this distance, it’s hard to even tell who’s fighting whom.

Trying to make all of it make sense are a bunch of 20- and 30-year-olds in dusty tan fatigues with rifles slung over their shoulders. American soldiers and Marines and airmen and sailors.

American servicemen are deployed in harm’s way in Syria, in Iraq, in Afghanistan, in Africa and elsewhere in Asia where the most recent campaigns of The War on Terror are taking place. Others are deployed where harm might still come looking: the Korean Demilitarized Zone, aboard ships near China, and on various drug interdiction missions in Central and South America. Even the servicemen based in Europe are there to keep an eye on Russia, our adversary for most of the last century.

When everything goes bad, these are the men and women the U.S. sends to fix it.

In answering that call, they carry on a tradition as old as our country.

The men fighting today in Syria — their fathers fought in the first Iraq War, their grandfathers in Vietnam. Their great-grandfathers stood against the expansion of North Korea or Nazi Germany or Imperial Japan.

Each of those conflicts demanded sacrifice. World War II claimed 407,000 American military lives  — roughly one-third of all the American service deaths since the country was founded. The survivors did not return unscathed, either. While earlier generations of veterans did not speak of their difficulties, we know some of them suffered from PTSD, substance abuse and suicide just as some veterans of more recent wars have.

Monday is Veterans Day, a day set aside to honor the men and women who “fought them over there so we didn’t have to fight them over here.”

When we look back on what our veterans have accomplished, the challenges they faced — and the sacrifices they made for our nation’s sake — the words “Thank You” seem wholly inadequate.