Politics and political views are incendiary by their very nature.
If you don't enjoy the freedoms given you by the veterans in this country, you are free to seek residence outside of the USA. A person can be a veteran and still NOT be pro-war. The person is doing their duty as a citizen.
You opened your mouth and while veterans are not a protected group, you have invited in people who feel opposite of you. Sure, you can sue him if you want to be made a laughingstock and seen as a non-patriot scumbag who doesn't treasure the freedom as afforded by others sacrificing themselves --and often their very lives--to protect you and yours.