Obama campaigned on the promise that he'd carry the fight to the Taliban in Pakistan, and he has, in addition to renewed effort in Afghanistan. He said all this before he was elected.
"The Left", as others put it, hasn't been against the Afghan effort nearly so much as against the way it's been handled in the past, a half-assed way to create perpetual quagmire and make money off it. The Bush Clan had their eyes on the real prize, Iraq, and left the Afghan situation to fester, quite knowingly.
Any body who can look at a globe will understand that Pakistan is our only real access to Afghanistan. The corrupt central asian dictatorships to the north are entirely unreliable, and landlocked, as well. Well, unless we want to reach an accord with the Iranians, which seems unlikely.
And for a guy who regularly raves on about how Israel doesn't need the US, IHV sure is whining about what they're not getting...