WASHINGTON

The US State Department made a determination approving a possible sale of F-100 frigate mid-life upgrade and related equipment to Spain, the Pentagon said on Thursday.

The estimated cost is $1.7 billion, the Defense Security Cooperation Agency said in a statement.

"The proposed sale will improve Spain's capability to meet current and future threats by affording more flexibility and capability to counter regional threats and continue to enhance stability in the region," it said.

The principal contractors will be Lockheed Martin, RTX Corporation, Ultra Maritime Naval Systems and Sensors, and General Dynamics.

Last year, Spain’s Council of Ministers gave the green light to the signing of the execution order for the mid-life modernization of the F100 frigates, ‘Alvaro de Bazan’ class. State-owned shipbuilder Navantia will undertake the work, which has an estimated value of €3.2 billion ($3.3 billion).