I'm over 20 years late with this assessment. "Watchmen" was published when I was working for RN in New York, practicing almost weekly counter-journalism on his behalf.
Missed this one, Mr. President. Got most of them.
Sadly, the graphic novel's alt.-Richard Nixon gets a raw deal. His high point comes in chapter IV, when he sends Dr. Manhattan, a blue superman with seemingly infinite powers, to defeat the Viet Cong (p. 20), enabling RN to ram through a constitutional amendment in 1975 that enables him to run for a third (and presumably a fourth and fifth) term (21).
From there, for Hannah Nixon's good Quaker son, it's downhill fast toward near-certain nuclear holocaust. I recognize that this is just a comic book, but author Alan Moore, although some kind of genius, misses or ignores that RN discerningly engaged the Soviets through his policy of detente, thus substantially decreasing East-West tensions. Moore might be saying that Nixon's policy, extrapolated into the 1980s, would've been too soft, resulting in the story's October 1985 Soviet invasion of Afghanistan -- which actually happened in 1979 under the dovish Jimmy Carter. And yet reviews of the "Watchmen" film make clear that among Moore's original targets was the hawkish Reagan administration.
If Nixon had really been in office, presumably the Soviets, in calculating the risks of aggression, would've remembered the tough measures he took in Vietnam (prior to sending the giant blue man, of course). When the alt.-Soviets nonetheless prepare to invade Pakistan, alt.-Nixon seems less than appalled at his advisers' estimation of the vast losses that would result from a nuclear exchange beginning with a U.S. first strike. "Losing the East Coast, we'd need to," he says. "I don't know...I'd always kind of hoped that the big decision would rest with somebody else. This is going to take some thinking about....I think we'll give it a week, gentlemen, before bringing out our big guns...After that, humanity is in the hands of a higher authority than mine. Let's just hope he's on our side." (III, 26-28)
Though each Cold War President no doubt dreaded having to make that decision, the distinct possibility of nuclear war shadowed three generations of Americans. For most of the era, the uneasy peace between the U.S. and Soviet Union was bolstered by the concept of mutually assured destruction. Both sides had enough nuclear firepower to be able to destroy the other, meaning that in a full-scale exchange, neither side could win. What altered the picture was the possibility that one side would have enough forces to destroy enough of the enemy's strategic nuclear missiles in a first strike that the attacker would stand a good chance of surviving as a functioning polity.
While the very idea of a survivable first strike was monstrous, it was the way strategists thought. "Watchmen" author Moore was deftly probing the weak link in the MAD armor, namely whether any leader, American or Soviet, would be ruthless, desperate, or unhinged enough to order the catastrophic first strike.
That's where Moore's choice of a guinea pig came in. His real-life 1985 commander in chief was Reagan, and the policy he was critiquing was Reagan's. When Reagan proposed his Strategic Defense Initiative in the early 1980s, as "Watchmen" was being envisioned and written, skeptics actually feared that Reagan was using it to create or enhance the U.S.'s first-strike capability. And yet for his madman, the monster actually willing to pull the trigger, Moore maneuvers poor Mr. Nixon back into office. To add insult to injury, he even has a character mutter about the privations of "Nixononmics." (VIII, 2) Near the end of the story, alt.-RN arrives at what looks like NORAD, clutching the nuclear football (it's actually a metal football, chained to his wrist), mumbles something about Mrs. Nixon being safe elsewhere, and then sits stoically, watching the big TV screens and waiting to give the order for a first strike if necessary. (X, 1-3)
Meanwhile, his actual Presidency was dedicated in large part to making sure no one would ever have to. Anti-Soviet hawks, including some proto-neocon Democrats, accused him and Henry Kissinger of degrading U.S. nuclear forces and even ceding a first-strike capability to Moscow. Pentagon generals were so nervous about RN's policies that they spied on him. Now that would make a great comic book.