In his first trip abroad as U.S. Secretary of State, John Kerry spoke to a Facebook gathering of youth in Berlin. One questioner asked “And since you have served the Army [actually Kerry served in the Navy], what exactly made you an opponent of the Vietnam War and maybe of war in general?”

Kerry answered that he went to Vietnam because he wanted to serve his country, and his country’s leaders said that the conflict there had “strategic implications for the country.” Instead he came to believe that the conflict was NOT strategic to America’s interests but was instead a civil war between Vietnamese. That’s why he led Veterans Against the War on his return.

Some wars must be fought, when America’s interests are directly attacked, Kerry said, but not “wars of choice.” Others have warned against being drawn into war when American interests are not directly affected.

Kerry was careful to emphasize our strong relationship with the European allies he is visiting, because they are based on mutual interests of strong democracies in a dangerous world. For decades we helped protect allies there from the Soviet Union until democracy replaced most of the communist regimes in eastern Europe. Europe was and is a strategic interest for us.

But what about countries like Syria and Iran? The U.S. and Europe have an interest in the war in Syria not turning into a dangerous regional conflict, with terrorists gaining a foothold, and Iran not becoming a nuclear power. We do not, however, want to send troops into what is a civil war.

These will continue to be subjects Kerry and others will discuss with allies. The ghosts of Vietnam, Iraq, and Afghanistan will stand as backdrop to their decisions.

At each step on Kerry’s trip, Syria and Iran have been topics of discussion. How do we encourage the non-terrorist opposition without ourselves become too embroiled in this civil war? How do we find the “right” sides to aid?