There's more than one way to skin an atom, and apparently Iran is trying them all. The rogue state may have weapons grade plutonium by next summer, US and European officials tell the Wall Street Journal, which is something of a surprise, given that until now the international community has been focused on Iran's uranium enrichment. To generate plutonium, Iran will need a heavy water reactor—like the one it's been building in recent months in Arak.
The site is above ground, and hence vulnerable to airstrikes—and officials worry that the development makes it even more likely that Israel will launch one. While the IAEA has been monitoring the Arak site from the start, the Journal says its potential importance "has vastly shot up" for Western officials recently. "It really crept up on us," an IAEA official says.