Additional reporting by Arie Egozi in Tel Aviv

Israel has decided to increase its acquisition of Lockheed Martin F-35 Lightning II fighters by 25 aircraft, which will bring its fleet to 44 of the fifth-generation type.

The country’s second contract, which is not yet finalised, was approved in principle when Israeli Defense Minister Moshe Ya’alon recently met with his US counterpart, Defense Secretary Chuck Hagel, in Washington DC.

Israel has already purchased 19 of the aircraft, at a cost of $2.75 billion. The first two F-35s are due to arrive in Israel by early 2017 and the rest should be delivered by 2018. The Israeli air force (IAF) plans to base the aircraft at Nevatim airbase in the southern region of the country.

The F-35's wings will be built in Israel by Israel Aerospace Industries (IAI) and Lt Gen Christopher Bogdan, the Pentagon’s F-35 programme chief, plans to visit Israel next week for the official inauguration of the wing production line. IAI will begin delivery of F-35 wings to Lockheed Martin in mid-2015.

The decade-long contract for F-35 wing production is part of Lockheed’s plan to share manufacturing cost and responsibility among its partner nations, although Israel is technically a foreign military sales customer under US law. The contract is worth up to $2.5 billion.

IAI has invested substantially in the advanced systems and technologies required to produce the wings since signing the contract in April 2013 and has established a dedicated production line to carry out the work.

Lockheed recently reached an agreement with the US government for the eighth lot of low-rate initial production (LRIP), which comprises 43 aircraft. This represents 29 of the type for the USA and the remaining 14 for international customers, including four for the UK, two for Norway, two for Italy, four for Japan and two of Israel’s initial buy of 19 aircraft.

As international partner purchases begin to be made, the price per aircraft – a perpetual concern – is meant to come down. Neither Lockheed nor the US government has released a figure for the LRIP 8 contract because it has not yet been finalised.

“Cost details will be released once the contract is finalised; however, in general, the average unit price for all three variants of the airframe in LRIP 8 is approximately 3.6 percent lower than the previous contract,” Lorraine Martin, Lockheed’s F-35 chief, says in a prepared statement.

LRIP 7, with conventional takeoff and landing engines – bought under a separate contract from manufacturer Pratt & Whitney – was worth $115 million per aircraft, so the 3.6% figure would mean lot eight should have unit costs of around $110.6 million.

The US Navy is set to begin testing of its carrier-based version of the Lightning II, the F-35C, aboard the USS Nimitz aircraft carrier on November 3 when an example will land aboard the vessel in the Pacific Ocean.