The US president should have someone reporting directly to him, who has no other mission other than “to wake up every morning thinking: 'What can I do today to keep nuclear weapons out of the hands of terrorists?'” That 2002 recommendation comes from a report co-authored by John Holdren, who is now scientific adviser to US president-elect Barack Obama. It is good news that Holdren understands the key nuclear non-proliferation issues, as bold US leadership is urgently needed to renew such efforts, especially given the damage done to these initiatives under the administration of George W. Bush (see page 250).

Holdren also understands that getting the international cooperation, and impetus, needed to revitalize non-proliferation will demand that the United States and other nuclear-weapons states make greater efforts to reduce their own arsenals and stockpiles. Obama could relay a strong message here by sending the Comprehensive Test Ban Treaty to the Senate for ratification.

Incomprehensibly, there is no complete inventory of stocks of highly enriched uranium.

Tangible steps could also be taken at once to substantially reduce the immediate threat of nuclear terrorism. What has been lacking is political will: a trade deal on bananas gets greater political priority than does non-proliferation. National and international measures to counter nuclear terrorism remain scandalously spartan and fragmented, and not remotely commensurate with the scale of the threat.

US support for all non-proliferation has been flat at between $1 billion and$1.5 billion annually over the past decade, or around 0.2% of total US defence spending. Flat too has been support for the International Atomic Energy Agency — the watchdog responsible for ensuring that national civil nuclear efforts remain civil — which remains hamstrung by the lack of any official remit to tackle the newer threat of nuclear terrorism (see Nature 451, 745; 2008).

The know-how to make a rudimentary nuclear weapon is already out there in the wild and cannot be recalled. But non-state players lack the means to produce the base fissile material needed: either highly enriched uranium (HEU) or plutonium. Blocking the theft or diversion of the vast stockpiles of these materials worldwide is therefore the most urgent issue for the international community.

HEU is the biggest worry. A plutonium device involves compressing a sphere of the metal with high explosives and would be a stretch for terrorists. An HEU device, by comparison, is child's play, demanding little more than a few dozen kilograms of the material and a simple mechanism to achieve a high-speed collision. Even a fizzle of an HEU device would take out most of Manhattan.

Incomprehensibly, there is no complete inventory of HEU stocks. But some 50 or so tonnes of it is thought to be stored in poorly secured civilian facilities worldwide, according to estimates by the Nuclear Threat Initiative in Washington DC. Most of that is used for research and medicine, for example in neutron sources and the production of medical isotopes. Low-enriched uranium (LEU) alternatives are available in almost all cases, but the extra costs involved, and the reactor redesign and extra research needed, have hampered efforts to switch over.

That some 272 HEU reactors in 56 countries remain largely unsecured is simply unacceptable. All civilian HEU facilities must either promptly switch to LEU or be given military-level security.

Securing HEU is just one of many non-proliferation issues — from Iran and North Korea to reductions in arsenals and missile defence — that will be on Obama's plate. But the time is ripe for a renewed global non-proliferation effort to avoid the world having to ask the day after a nuclear terrorist attack: “How did we fail to see this coming; why didn't we do something about it before?”