Arms deals with Arabian Gulf countries helped push United States weapons sales to a record $66.3 billion (Dh243.5bn) last year, a report for the US Congress found.
The tripling in sales compared to 2010 represents growing concerns among Gulf states and their American allies about the possibility of a nuclear-armed Iran as well as a more fragile region in the aftermath of the Arab Spring.
"It's clear that the Gulf countries are very apprehensive of Iran, and that is one of the key reasons why these countries are spending significant money on advanced arms," said Pieter Wezeman, who studies arms transfers at the Stockholm International Peace Research Institute.
An agreement to supply Saudi Arabia with helicopters and fighter jets accounted for about half the total for last year, at $33.4bn. The report by the non-partisan Congressional Research Service, a division of the Library of Congress, said US firms last year agreed to deliver 84 F-15 fighter jets and dozens of Apache and Black Hawk helicopters, as well as the missiles and parts to service the aircraft.
The fighter jets, Mr Wezeman said, could be used either in national defence or against aggression closer to home, for example in targeting rogue elements in neighbouring Yemen.
The UAE also signed significant deals with the US last year, purchasing Chinook helicopters valued at $939m and anti-missile shield technology worth $3.49bn. Oman signed a $1.4bn deal for 18 F-16 fighter jets.
This year, figures for which are not included in the report, the US has signed weapons deals with Kuwait and Bahrain estimated at $4.2bn and $53m, respectively.
Such weapons deals are often interpreted as signals of US diplomatic support - or lack thereof - for the recipient country. This year's arms deal with Bahrain, for example, was held up in Congress for several months over concerns about its government's handling of protests last year.
American-Gulf cooperation on a host of security issues has improved following the Arab Spring, a senior US official said in an interview with The National last month. Amid a region in tumult, the official said, "We [the US] are looking primarily at the Gulf Cooperation Council and ways to cooperate more strategically with the GCC on military, security, and trade."
But analysts cautioned that the sales are also indicative of economic realities in the US, where tighter budgets have shifted the defence industry's gaze toward exports.
In the case of fighter jets, for example, the US has delayed production of its own next generation of aircraft. Had the deal with Riyadh not been signed, manufacturers might have had to shut down production altogether, said Mr Wezeman.
Although the Gulf arms market is expected to remain strong in coming years, this year will probably prove to be an anomaly for US sales because of the large Saudi deal. The $66.3bn figure represents the value of all arms deals signed but the weapons and aircraft will be delivered as far as several decades out.