The B-57E version of the plane was the first aircraft in the U.S. inventory specifically built for towing aerial targets. The B-57E could be converted to a bomber and a number of them were converted to replace combat loses in Vietnam!
The B-57 is one of only two major combat aircraft of foreign design adopted for use by the US military since the end of World War II. The first British built Canberra arrived in the US in 1951 and US built aircraft began flying 2 years later!