You certainly remember the forged Nigerien papers, used to justify the Iraq invasion, that purported to show Niger sold yellowcake to Iraq. And you may recall the analogous "greensalt" papers which, in 2004, purported to show that Iran was trying to build a nuclear missile capability.
An anonymous source at the International Atomic Energy Agency, which discredited the Niger papers, is now claiming that the Agency is doing the same for the greensalt papers. The smoking gun was an original document produced by Iran, which was compared with a version produced by the US.