The Pentagon has reportedly notified Congress of plans to procure new spy planes from Northrop Grumman, in a deal worth approximately $3.9bn.

An undisclosed source was quoted by Reuters as saying that the five-year deal, which could be confirmed by the end of June, will provide $369m in savings.

It will cover 25 E-2D Advanced Hawkeye aircraft, which are to be used on aircraft carriers, the source added.

"An undisclosed source was quoted by Reuters as saying that the five-year deal, which could be confirmed by the end of June, will provide $369m in savings."

Aimed at replacing the E-2C aircraft deployed by the US Navy, the E-2D Advanced Hawkeye integrates a new radar, theatre missile defence capabilities, multi-sensor integration and a Northrop Grumman tactical-glass cockpit.

The aircraft will also incorporate Lockheed Martin's AN/APY-9 solid-state, electronically steered UHF radars, which are being supplied under the E-2C radar modernisation programme.

The US Navy received its first E-2D Advanced Hawkeye production aircraft in July 2010, under a $432m low-rate production contract for four aircraft, awarded in June 2009.

Furthermore, Northrop also received a $795m contract for the design, manufacture and supply of five LRIP E-2D Hawkeye aircraft, together with long-lead materials, in 2011.

With the successful launch of the E-2D through a prototype electromagnetic aircraft launch system (EMALS) in September 2011, its initial operational capability is scheduled for October.