Um, I'd imagine the Left as being more likely to launch nuclear attacks on American soil than the Right would be.
Oh, and in the event of a new Civil War, the Blue States would be mercilessly crushed, largely because we in the Red States have something they will never have: Unity.
A civil war requires that the people of one side band together, cast aside their petty differences, and unite for a common cause. Problem is, the Left cannot achieve this unity, as their self- righteous love affair with "Diversity" means their side has many factions that are virulently opposed to each other (Radical Muslims vs. Radical LGBTs, radical feminists vs. Transgender activists, radical environmentalists vs. Labor unions in industries that environmentalists oppose such as logging and mining, etc.), and are incapable of setting aside their differences. Hell, look at how many DU posts inevitably descend into bickering and infighting.
The Blue States' forces will thus be far more likely to destroy each other through infighting than to destroy us.
Here are a couple suggestions on strategies to further exacerbate this:
1. As the Red States have a near- monopoly on agriculture and food production, immediately cut off all food deliveries to the Blue States, and broadcast to the people in the Blue States that we have done this and will resume food deliveries to each Blue State when and only when that state unconditionally surrenders. Their people will immediately panic, and every crumb of food in the Blue States will be bought or stolen in a day, and eaten in no more than a week and a half. Within a week after that, the starving people in those states will be rioting, fighting each other over what's left of the food (The Blue States do have some farming and food production, but nowhere near enough to meet demand), and pressuring their leaders to surrender.
2. As most leftists are drug addicts, another strategy is to use intelligence resources to identify and locate as many of their marijuana farms, crackhouses and meth labs as possible. Then, over the course of a day or so, launch a series of black- ops strikes to take out each of them at once. Burn their pot plants, smash their equipment, flush their supplies, all of it. Then, make sure to block their allies in the Mexican cartels from being able to bring more supplies in. Then, wait for the druggies to inevitably start killing each other for what's left of the dope. I got the idea for this from something that happened when the Occupy movement was at its strongest: In one Occupy camp, one Occupier was shot and killed by another Occupier in a fight over a baggie of pot.
So, after letting them tear each other limb from limb for a while, we step in, and what's left of them will be starving, going through severe withdrawal, and pose no real resistance.
Thus, we win with very few casualties on our side.