LAST month the emirate of Abu Dhabi held the International Defence Exhibition and Conference (IDEX), the Middle East's largest arms fair. The four-day event was a roaring success, playing host to 1,235 exhibitors and a record number of delegates. On the last day, the United Arab Emirates announced $5.2bn worth of weapons purchases from suppliers including France, Russia and America. The Gulf state’s hunger for big guns is hardly exceptional. The Stockholm International Peace Research Institute (SIPRI), a think-tank, recently released data showing that transfers of big weapons in 2012-16 reached their highest volume for any five-year period since the end of the cold war. At a time when international trade is flagging, why is the global arms trade doing so well?

The frail security balance of an increasingly multipolar world has many countries worried. Since the end of the cold war, scholars have found that greater instability—both internal and external—has tended to be correlated with a rise in military spending, as intuition would suggest. What has changed in recent years is that a larger share of the money is going towards imports: in contrast with the 2000s, when the West’s armies undertook the bulk of the fighting in Afghanistan and Iraq, many nations sucked into this decade’s disputes lack military muscle and have no domestic industry capable of building it up. With America less eager to be the world’s policeman, they see a greater need for buying their own kit. Vietnam, which borders the South China Sea, imported three times more weaponry in 2012-16 than in 2007-2011. Saudi Arabia’s purchases grew by 212% and Qatar’s by 245%.

But the trade is also underpinned by a push on the supply side. America, which sells arms to more than 100 countries, dominates the market. As technology improves, it is helping retool developing nations’ arsenals with modern gadgets, such as GPS guidance and automated systems. Its exports grew 42% from 2008 to 2015. Other exporters see a lucrative market too. China, known in the 1990s for its knock-offs of Western equipment, has emerged as a top-tier supplier. Its flagship tankmaker celebrated the country’s participation at IDEX this year by taking over one of the fair’s largest stands. South Korea sells aircraft and warships to Latin America. Russia is building on its cold-war legacy business.

The proliferation of conventional weapons is a source of volatility in itself. Yet measures to contain them have been feeble. Unlike nuclear treaties, conventional-arms-control regimes focus on making sure weapons aren't sold to irresponsible users, rather than promoting disarmament. Even within this narrower scope their efficacy remains unproven. The UN-led Arms Trade Treaty, the first global attempt at regulating the business, is only two years old. China and Russia are not signatories; America has yet to ratify it. Together, these three countries account for more than 60% of exports. Existing regional control instruments, such as the EU Code of Conduct on Arms Exports, have a patchy record of blocking controversial sales. In some regions, including Asia and the Middle East, there simply are no such treaties. Meanwhile a sizeable increase in military spending in America, as proposed by itspresident last week, may also prompt others to go shopping again. Expect arms trade shows—along with the arms trade—to boom.