Jeff Jacoby has a good smackdown:

The founders of the American republic were unambiguous in rejecting any hint of military supremacy. Under the Constitution, military leaders take their orders from civilian leaders, who are subject in turn to the judgment of ordinary voters. Those who wear the uniform in wartime are entitled to their countrymen’s esteem and lasting gratitude. But for well over two centuries, Americans have insisted that when it comes to security and defense policy, soldiers and veterans get no more of a say than anyone else.

You don’t need medical training to express an opinion on healthcare. You don’t have to be on the police force to comment on matters of law and order. You don’t have to be a parent or a teacher or a graduate to be heard on the educational controversies of the day. You don’t have to be a journalist to comment on this or any other column.

And whether you have fought for your country or never had that honor, you have every right to weigh in on questions of war and peace. Those who cackle “Chicken hawk!” are not making an argument. They are merely trying to stifle one, and deserve to be ignored.