In the aftermath the terrorist attacks against the United States in September 2001, President George W. Bush warned of the consequences of terrorist groups or rogue states of acquiring nuclear materials. At the time, top White House officials warned: "The problem here is that there will always be some uncertainty about how quickly [Iraq] can acquire nuclear weapons. But we don't want the smoking gun to be a mushroom cloud." It is ironic that the overthrow of Saddam Hussein's regime in 2003 was predicated on the basis of preventing Iraq from developing nuclear weapons or providing nuclear materials to terrorist groups that could then be used in a so-called ‘dirty bomb', which is designed to spread nuclear materials by combining it with a conventional explosive. The irony is that the instability the US-led invasion of Iraq created has helped contribute to the emergence of the fierce Islamic militant organization, Islamic State of Iraq and Syria (ISIS)—or simply the Islamic State—which now controls vast swathes of territory stretching from western Syria to northern Iraq. Unexpectedly, the ISIS takeover of vast swathes of northern Iraq has raised the possibility of the very situation that the Bush administration warned of. According to a July 8 letter from Iraq's Ambassador to the United Nations, Mohamed Ali Alhakim, to UN Secretary-General Ban Ki-moon, of which Reuters obtained a copy, when ISIS militants seized the northern Iraqi city of Mosul, the country's third largest city, in early June 2014, it managed to acquire nearly 40 kg (88 pounds) of "low grade" uranium compounds used for scientific research at the University of Mosul. According to the BBC, Alhakim wrote, "Terrorist groups have seized control of nuclear material at the sites that came out of the control of the [Iraqi] state." He added: "These nuclear materials, despite the limited amounts mentioned, can enable terrorist groups, with the availability of the required expertise, to use it separately or in combination with other materials in its terrorist acts." As dire as this may seem, the International Atomic Energy Agency (IAEA) and the international community have tempered their responses. "On the basis of the initial information we believe the material involved is low grade and would not present a significant safety, security or nuclear proliferation risk," IAEA spokeswoman Gill Tudor said. "Nevertheless, any loss of regulatory control over nuclear and other radioactive materials is a cause for concern." Significantly, the loss of the nuclear materials has not raised alarm among nuclear proliferation experts. According to Olli Heinonen, a former IAEA chief inspector, the materials from the university were not suitable for a dirty bomb and did not seem to pose a threat to international security. He said the uranium compounds were likely laboratory chemicals or radiation shielding, consisting of natural or depleted uranium. He told Reuters, "You cannot make a nuclear explosive from this amount, but all uranium compounds are poisonous". Even so, the international community expressed alarm about the stealing of nuclear materials. According to the Voice of Russia, a Foreign Ministry official, Alexander Lukashevich, told reporters, "We are extremely concerned about the transition of this important facility into the hands of militants that not only leads to breakdown of deadlines for destruction of the Iraqi chemical weapons agreed upon with the [Organisation for the Prohibition of Chemical Weapons], but also represents a serious threat from the point of view of a possible use of the seized materials by extremists not only in Iraq but also in the neighboring countries, including Syria." A State Department spokeswoman, Jen Psaki, downplayed concern over the uranium. "I would point you to the comments and the statement made by the IAEA today, that they believe the material involved to be low-grade and not presenting a significant safety, security, or nuclear proliferation risk," adding, "of course, [the IAEA is] the appropriate identity to make any decision about whether there is a risk or concern, but it doesn't seem that is the case at this point in time." In the end, it seems unlikely that ISIS's theft of the nuclear materials pose a direct threat to international security. Even so, the collapse of both the Iraqi and Syrian states pose significant new challenges to the international community and the risk of proliferation, far greater than any that existed in the immediate aftermath of 9/11.