As the White House announced that President Barack Obama would visit Hiroshima, Japan, next week, it immediately pledged that he would not apologise for the United States dropping atomic bombs on that city and Nagasaki during the Second World War. But the real reckoning in Hiroshima should be about the future of nuclear weapons, not the past. Unless the President acts and speaks forthrightly, his visit may mark not only the ashes of Hiroshima, but also the ashes of his promise to move towards a world freed of the threat of nuclear annihilation.

In his first major foreign policy address, delivered in Prague in April 2009, Obama trumpeted “America’s commitment” to a “world without nuclear weapons”. To accept their continued existence, he warned, was to accede to their eventual use. But the use of even a single nuclear bomb was too horrible to contemplate. Nuclear disarmament, he acknowledged, would not come easily or quickly. It would take “patience and persistence”, but the goal of complete disarmament should drive strategy and concrete actions.

Some important steps were taken after that speech. Substantial reductions in nuclear weapons were negotiated with Russia, and remain on track. The role of nuclear weapons was reduced in US national security strategy. The successful Iran negotiations curbed the threat of Iranian nuclear weapons development and revived momentum for the nonproliferation movement. World leaders focused new attention on the threat of nuclear terrorism. The President hosted summits focused on securing loose nuclear weapons-grade materials across the world.

But 15,000 nuclear weapons remain in the world. The United States and Russia keep thousands on hair-trigger alert. The Senate blocked ratification of the Comprehensive Test Ban Treaty. Objections from Pakistan have frustrated progress on a Fissile Material Cut-off Treaty.

The administration’s Nuclear Weapons Employment Strategy limits the use of nuclear weapons to “extreme circumstances”, but does not rule out first use of them. The administration has committed to creating a new generation of nuclear warheads and the systems that deliver them, estimated to cost $1 trillion over the next three decades. Nato’s anti-ballistic missile system just went live in Romania, despite Russian objections that it violates the 1987 Intermediate-range Nuclear Forces Treaty. Russia is responding to the US build-up on its borders by threatening to move nuclear-armed Iskander missiles to the Polish border. The US denounces that as a violation of the INF Treaty also.

Former defence secretary William Perry warns flatly that “the danger of a nuclear catastrophe today is greater than during the Cold War”. Perry points to not only the terrorist groups such as the Islamic State that would buy or steal nuclear weapons-grade materials, but also the rising tensions between Russia and the US.

On the eve of his fourth and last Nuclear Security Summit in Washington, Obama once more reasserted that nuclear security will not be possible so long as nuclear weapons exist. “As the only nation ever to use nuclear weapons,” he wrote in a Post op-ed, “the United States has a moral obligation to continue to lead the way in eliminating them”.

The President calls for “patience and persistence”. But what we have witnessed is the power of old ideas, large bureaucracies, entrenched interests and renewed enmities to strangle even modest efforts to move in a new direction.

To reverse course, some clear and bold steps are needed. US nuclear weapons should be taken off hair-trigger alert. Nuclear weapons should be limited only to deterrence, not to be used in any other circumstance. Building a new generation of nuclear weapons should be shelved in favour of recommitting to efforts to pursue a course to rid the world of these weapons.

The US, Perry argues, could sensibly get rid of its ground-based missiles and warheads, which are both vulnerable and redundant. The President should act to engage Russia and seek to reduce the growing tensions that threaten to lead to a dangerous new build-up. The President might use the trip to Hiroshima to summon the United Nations to prepare a global summit to define the path to a verifiable elimination of nuclear weapons.

The President’s trip to Hiroshima cannot undo the past. What it can do is mark a renewed commitment to a future without nuclear weapons. But for the words to have any meaning, they have to be accompanied by deeds. The President still has time to act.

Katrina vanden Heuvel, editor and publisher of the Nation magazine, writes a weekly online column for The Washington Post