The orders are worth $3.2 million, the company said, and the systems are to be delivered immediately and continue through the year.
The AquaShield provides automatic detection, tracking and classification for both scuba and closed-circuit divers and is used by navies, homeland security agencies and others -- such as oil and gas companies, nuclear power facilities and port authorities.
DSIT said the unidentified customer is already using its AquaShield Diver Detection Sonar and PointShield Portable Diver Detection Sonar systems for protection of the country's critical assets.
"We regard this navy as one of our most important customers," said Dan Ben-Dov, vice president of DSIT's Sales and Marketing unit. "We are well aware of their very strict operational requirements and performance standards. Obtaining this repeat order, which comes following their use of DSIT's underwater port security systems for several years, reveals their high level of satisfaction."