Weapons sales by the United States tripled in 2011 to a record high, driven by major arms sales to Persian Gulf allies concerned about Iran’s regional ambitions, according to a new study for Congress.

Overseas weapons sales by the United States totaled $66.3 billion last year, or more than three-quarters of the global arms market, valued at $85.3 billion in 2011. Russia was a distant second, with $4.8 billion in deals.

The American weapons sales total was an “extraordinary increase” over the $21.4 billion in deals for 2010, the study found, and was the largest single-year sales total in the history of United States arms exports. The previous high was in fiscal year 2009, when American weapons sales overseas totaled nearly $31 billion.