The limits are vague on Iran’s research and development of advanced technology that could be used for producing nuclear weapons. Inspectors still might not be able to enter Iranian military sites where nuclear work previously took place. The Americans and Iranians already are bickering over how fast economic sanctions on Iran would be relaxed. And Obama’s assertion that the penalties could always be snapped back into force is undermined by the U.S. fact sheet describing a “dispute resolution process” enshrined in the agreement.

But the biggest issue may be one U.S. officials have emphasized above all others: the “breakout time” Iran would need to surreptitiously produce a nuclear weapon. The framework imposes a combination of restrictions that would leave Iran needing to work for at least a year to accomplish that goal, rather than the two-to-three months currently.

Obama and Secretary of State John Kerry have cited the longer breakout period as proof they’ve secured a “good deal” and say the one-year window is enough time for the U.S. to detect a covert Iranian push toward a bomb and to respond.

That standard would hold only for a decade, however. Over the following five years, it’s unclear how far Iran’s nuclear program would be kept from the bomb.