United States

While in office, President Barack Obama reviewed Homeland Security policy and concluded that "attacks using improvised nuclear devices ... pose a serious and increasing national security risk". In their presidential contest, President George W. Bush and Senator John Kerry both agreed that the most serious danger facing the United States is the possibility that terrorists could obtain a nuclear bomb. Most nuclear-weapon analysts agree that "building such a device would pose few technological challenges to reasonably competent terrorists". The main barrier is acquiring highly enriched uranium.

In 2004, Graham Allison, U.S. Assistant Secretary of Defense during the Clinton administration, wrote that “on the current path, a nuclear terrorist attack on America in the decade ahead is more likely than not". In 2004, Bruce Blair, president of the Center for Defense Information stated: "I wouldn't be at all surprised if nuclear weapons are used over the next 15 or 20 years, first and foremost by a terrorist group that gets its hands on a Russian nuclear weapon or a Pakistani nuclear weapon". In 2006, Robert Galluccii, Dean of the Georgetown University School of Foreign Service, estimated that, “it is more likely than not that al-Qaeda or one of its affiliates will detonate a nuclear weapon in a U.S. city within the next five to ten years." Despite a number of claims, there is no credible evidence that any terrorist group has yet succeeded in obtaining a nuclear bomb or the materials needed to make one.

Detonation of a nuclear weapon in a major U.S. city could kill more than 500,000 people and cause more than a trillion dollars in damage. Hundreds of thousands could die from fallout, the resulting fires and collapsing buildings. In this scenario, uncontrolled fires would burn for days and emergency services and hospitals would be completely overwhelmed. The likely socio-economic consequences in the United States outside the immediate vicinity of an attack, and possibly in other countries, would also likely be far-reaching. A Rand Corporation report speculates that there may be an exodus from other urban centers by populations fearful of another nuclear attack.

The Obama administration will focus on reducing the risk of high-consequence, non-traditional nuclear threats. Nuclear security is to be strengthened by enhancing "nuclear detection architecture and ensuring that our own nuclear materials are secure," and by "establishing well-planned, well-rehearsed, plans for co-ordinated response." According to senior Pentagon officials, the United States will make "thwarting nuclear-armed terrorists a central aim of American strategic nuclear planning." Nuclear attribution is another strategy being pursued to counter terrorism. Led by the National Technical Nuclear Forensics Center, attribution would allow the government to determine the likely source of nuclear material used in the event of a nuclear attack. This would prevent terrorist groups, and any states willing to help them, from being able to pull off a covert attack without assurance of retaliation.

In July 2010 medical personnel from the U.S. Army practiced the techniques they would use to treat people injured by an atomic blast. The exercises were carried out at a training center in Indiana, and were set up to "simulate the aftermath of a small nuclear bomb blast, set off in a U.S. city by terrorists."

Stuxnet is a computer worm discovered in June 2010 that is believed to have been created by the United States and Israel to attack Iran's nuclear facilities.

Nuclear power plantsedit

After 9/11, nuclear power plants were to be prepared for an attack by a large, well-armed terrorist group. But the Nuclear Regulatory Commission, in revising its security rules, decided not to require that plants be able to defend themselves against groups carrying sophisticated weapons. According to a study by the Government Accountability Office, the N.R.C. appeared to have based its revised rules "on what the industry considered reasonable and feasible to defend against rather than on an assessment of the terrorist threat itself". If terrorist groups could sufficiently damage safety systems to cause a core meltdown at a nuclear power plant, and/or sufficiently damage spent fuel pools, such an attack could lead to widespread radioactive contamination. The Federation of American Scientists have said that if nuclear power use is to expand significantly, nuclear facilities will have to be made extremely safe from attacks that could release massive quantities of radioactivity into the community. New reactor designs have features of passive safety, which may help. In the United States, the NRC carries out "Force on Force" (FOF) exercises at all Nuclear Power Plant (NPP) sites at least once every three years.

The peace group Plowshares have shown how nuclear weapons facilities can be penetrated, and the groups actions represent extraordinary breaches of security at nuclear weapons plants in the United States. The National Nuclear Security Administration has acknowledged the seriousness of the 2012 Plowshares action. Non-proliferation policy experts have questioned "the use of private contractors to provide security at facilities that manufacture and store the government's most dangerous military material".

Hoaxesedit

In late 1974, President Gerald Ford was warned that the FBI received a communication from an extortionist wanting $200,000 ($1,000,000 today) after claiming that a nuclear weapon had been placed somewhere in Boston. A team of experts rushed in from the United States Atomic Energy Commission but their radiation detection gear arrived at a different airport. Federal officials then rented a fleet of vans to carry concealed radiation detectors around the city but forgot to bring the tools they needed to install the equipment. The incident was later found to be a hoax. However, the government's response made clear the need for an agency capable of effectively responding to such threats in the future. Later that year, President Ford created the Nuclear Emergency Search Team (NEST), which under the Atomic Energy Act is tasked with investigating the "illegal use of nuclear materials within the United States, including terrorist threats involving the use of special nuclear materials".

One of its first responses by the Nuclear Emergency Search/Support Team was in Spokane, Washington on November 23, 1976. An unknown group called the "Days of Omega" had mailed an extortion threat claiming it would explode radioactive containers of water all over the city unless paid $500,000 ($2,200,000 today). Presumably, the radioactive containers had been stolen from the Hanford Site, less than 150 miles to the southwest. Immediately, NEST flew in a support aircraft from Las Vegas and began searching for non-natural radiation, but found nothing. No one ever responded despite the elaborate instructions given, or made any attempt to claim the (fake) money which was kept under surveillance. Within days, the incident was deemed a hoax, though the case was never solved. To avoid panic, the public was not notified until a few years later.