The US defense secretary has ordered an immediate review of the Air Force One recapitalisation and Lockheed Martin F-35 programmes, following president Donald Trump’s earlier threats to lower the costs of both platforms.

In a 26 January memo, Defense Secretary James Mattis ordered the deputy secretary of defense to examine ways to reduce the cost of the both the F-35 and Air Force One replacement programmes. Lockheed’s stocks dropped sharply following Mattis’ announcement.

Under the presidential aircraft recapitalisation review, the White House Military Office and deputy secretary will identify specific areas where costs could be cut. This could include autonomous operations, aircraft power generation,cooling, survivability and communications capabilities, the memo states.

Although Trump has criticised the entire F-35 programme, the review will take only the C variant into consideration, which accounts for the smallest share of Lockheed’s programme of record. The Super Hornet needs a catapult to launch from a carrier and would not be able to replace the short-takeoff and vertical landing B variant.

“In parallel, the deputy secretary of defense will oversee a review that compares F-35C and F/A-18E/F operational capabilities and assess the extent that the F/A-18E/F improvements (an advanced Super Hornet) can be made in order to provide a competitive, cost effective, fighter aircraft alternative,” Mattis writes.

The decision to pit the F-35C against an advanced Super Hornet follows Trump’s 21 December tweet, which targeted the F-35 programme’s cost overruns and suggested Boeing price out a “comparable Super Hornet.” While even an advanced Super Hornet is unable to compete with the F-35 in terms of stealth, FlightGlobal previously noted the F/A-18E/F could provide a natural, non-very low observable (VLO) stealth replacement for the C variant. The Super Hornet could still perform well against less sophisticated threats.

A Super Hornet and F-35 battle has some precedent already. In November, Canada announced the government would purchase 18 Boeing F/A-18 Super Hornets as an interim fix for its current capability gap and later launch an open competition to replace its aging fleet of CF-18 fighter jets.

The C variant may represent a small margin of Lockheed’s production, but any decision by the U.S. Navy to reduce or abandon its buy would trigger a significant cost increase to the US Air Force, Marine Corps and international partners involved in the joint programme, Center for Strategic and International Studies analyst Andrew Hunter said earlier this week.

“Although there have been some changes on the international [partners], on the whole it’s held up very well over the last several years,” Hunter said. “But if the Navy fell off the table that would have a very profound impact on unit costs.”