Reza Aslan urges Iran and America to find one:
[T]his latest attack on innocent Iranian worshippers could provide an opportunity for American officials to begin coordinating with Iran in combating Jundallah and similar Sunni extremist groups who have found shelter in southeastern Iran and in Pakistan. Sound crazy? Perhaps, though similar coordination between U.S. and Iranian intelligence officials took place in 2001, during the invasion of Afghanistan, leading to a (very brief) warming of ties between the two countries.
Who knows? Maybe this kind of cooperation against a shared enemy is exactly what we need to realign the fraught relationship between the U.S. and Iran. The alternative is that Jundullah continues its inhuman assault against the Iranian public, the Iranian government continues to blame U.S. for those attacks, and the Iranian people, who tend to dismiss everything their government tells them, start actually to believe it.