AT THE outset of his presidency, Barack Obama laid out a vision of a nuclear-free world in what became known as the Prague speech. Such was the mood of optimism that Mr Obama was prematurely awarded the Nobel peace prize. Mr Obama did manage to get a new strategic arms-control agreement with Russia soon after and last year saw what the president almost certainly regards as his greatest foreign-policy achievement: the nuclear deal with Iran. Those apart, there is not much to show for that early statement of intent other than a series of four Nuclear Security Summits, the last of which wrapped up in Washington on April 1st.
The main aim of the summits has been to create a better system of global safeguards to ensure that nuclear material, specifically highly enriched uranium and plutonium, which could be used by terrorists to construct a so-called “dirty bomb”—or even a fission bomb—does not get into the wrong hands.
The summits have been a qualified success. Achievements so far include the removal of highly enriched uranium from 15 countries and the closure or conversion to low-enriched-uranium use of many research reactors and isotope-production facilities. For its part, the White House instructed the American navy to look into how it might convert the highly-enriched-uranium reactors that power its aircraft carriers and submarines.