In the days since President Obama announced he is massively escalating the Afghanistan War (and yes, a 30-40% troop increase is massive), it has become assumed fact that he is just fulfilling his campaign promise. The idea is that nobody has a right to be angry at him, because hey - he promised it!
Of course, that's an absurd notion in that (as Glenn Greenwald points out) you could similarly argue that hey - since George W. Bush promised in 2004 to escalate the Iraq War and privatize Social Security, nobody had a right to oppose that either...and nobody made that argument.
But even if you accept the "Obama promised an Afghan escalation so STFU" premise, it still doesn't really fly - because here's the thing everyone's forgetting: He never "promised" to double the size of the Afghanistan occupation. Not even close.
As you can see from Politifact and Newsweek, President Obama promised to send 2 more brigades. As the U.S. Army's website shows, a brigade is up to 5,000 troops, which means President Obama specifically promised to send 10,000 more troops to Afghanistan. He in no way promised send 47,000 more troops - or 9 brigades worth of troops - to Afghanistan, which is what he has done between his February escalation of 17,000 troops and now his December escalation of 30,000 more troops. And he in no way promised to send tens of thousands more private military contractors.
Now, sure, if you wanted to be obsequiously propagandistic in your fealty to President Obama, you could argue that he gave himself a two-word out when he made his Afghanistan campaign promise - he said he'd send "at least" two more brigades. So yeah, you could lawyer it to say that technically, he hasn't "broken" a campaign promise - just like Republicans lamely argued that even though Bush in 2000 said he was against nation building, he also said he wanted to protect America, and that latter clause meant his Iraq adventure wasn't breaking the promise in the former clause.
Yes, Obama maybe hasn't broken an explicit campaign promise on Afghanistan (while, of course, explicitly breaking promises on everything from NAFTA to Gitmo) - and he certainly didn't promise to end the Afghanistan War (nobody has said he did). But I'd say he also isn't simply "fulfilling" a campaign promise by escalating the troop increase he committed to by a factor of four (and again, that's only counting U.S. military troops, and not private contractors).
In fact, I'd say a lot of people have a right to feel exactly the way eminently esteemed historian Garry Wills feels: misled or perhaps even betrayed by a guy who campaigned against Bush's neoconservative foreign/military policy, and made a limited pledge of escalation, and now is going above and beyond the spirit of that pledge.