During his questioning of Gen. David Petraeus and Amb. Ryan Crocker at the Senate Armed Services Committee hearings yesterday, John McCain again confused — or deliberately conflated — the relationship between the Iranian regime, which is controlled exclusively by Shiites, and al Qaeda, a Sunni terror cult.

Here’s what McCain said:

SEN. MCCAIN: There are numerous threats to security in Iraq and the future of Iraq. Do you still view al Qaeda in Iraq as a major threat?

GEN. PETRAEUS: It is still a major threat, though it is certainly not as major a threat as it was, say, 15 months ago.

SEN. MCCAIN: Certainly not an obscure sect of the Shi’ites, all overall, or Sunnis or anybody else.

McCain’s confusion/conflation yesterday was the fifth time he’s made the mistake, according to an email sent out by the Democratic National Committee yesterday. If so, the first error may have been a slip of the tongue. The second time could have been misspeaking. The third may have been a brain fart. But the fourth time he confused Shias and Sunnis was simply egregious, and this fifth time may well be presenting for senile dementia.

On the other hand, Republicans have been talking up a purported threat from Iran whenever possible lately, and the Petraeus/Crocker hearings provided an excellent venue for fear-baiting. So maybe McCain was not confused at all. Maybe he has deliberately conflating Shiite Iran with its bitter Sunni enemies in order keep the GOP base too terrified to think rationally about, say, how Republican economic policies have devastated their family finances.

While the difference between the Islamic sects is obscure to most Americans, as it was to George Bush before he invaded Iraq, Shiites and Sunnis have been bitterly at odds for the better part of 12 centuries, and voters must demand that the next president have a comprehensive understanding of the blood lust of these internecine factions, which is at the core of the violence faced by U.S. occupation forces in the region.