Marc Ambinder tries to sum up the Kissinger issue:
The only difference appears to be that McCain would insist that Iran do certain things before diplomacy commences, while Kissinger and Obama would NOT insist on any concessions.
“Do certain things” means the dreaded preconditions. In short, Barack Obama favors negotiations without preconditions. I think this is the correct strategy. Henry Kissinger also thinks it’s the correct strategy. So when Obama says Kissinger agrees with him, Obama is correct. When McCain says Kissinger does not agree with Obama, McCain is incorrect. That McCain is incorrect is evident from the logic of Marc’s post, but he doesn’t quite seem to be able to bring himself to say it.