There is an interesting lack of symmetry when you consider dissenters when we are at war and dissenters when we are not.
If our national policy is that we are not at war with a country, taking personal action to harm that country is illegal. Individuals are not allowed to make war on their own. You cannot be a freebooter and expect to have your actions approved by the government.
But if our country is at war, it is "patriotic" to check out of the war and do all you can to make us end the war even if that means losing the war.