Can the US turn off European weapons? Experts weigh in on 'kill switch' fears

After US President Donald Trump initially walked back military support to Ukraine, German officials have voiced concern that the Americans could control one of the country’s newly procured weapons.

Germany inked a multi-billion euro deal with American aerospace giant Lockheed Martin in 2022 for 35 F-35A Lightning II aircraft. The Bundeswehr - Germany’s armed forces - procured a further eight F-35s last year.  

Joachim Schranzhofer, head of communications at German arms company Hendsolt, told the German newspaper Bild last week that a so-called "kill switch" put into American-produced F-35s is more than just a rumour, insinuating that it would be easy for the US to ground the aircraft by blocking access to key software, which remains under their control. 

Wolfgang Ischinger, the former chairman of the Munich Security Conference, and Ingo Gädechens, a former military officer and member of Germany’s Christian Democratic Union (CDU) party, also echoed this sentiment. 

A spokesperson from the German ministry of defence, however, told Euronews Next that there is no plan to cancel the purchase of F-35 fighter jets in light of the concerns raised. 

F-35 is the 'NATO standard fighter of choice'

According to the US Air Force, Lockheed’s "most common" F-35 model, the F-35A Lightning II, is a multirole fighter jet that pairs "stealth, sensor fusion and unprecedented situational awareness" in the sky. 

Lockheed describes the F-35 Lightening II as rapidly becoming the "NATO standard fighter of choice". 

Belgium, Czech Republic, Denmark, Finland, Greece, Italy, Netherlands, Norway, Poland, and Switzerland have F35s in their fleets. Romania signed an agreement with Lockheed Martin for the same aircraft in December as well. 

Lockheed Martin said in a statement last year that it expected over 550 F-35s to be in operation in 10 European countries by the end of the decade and that these weapons have "increased interoperability in Europe". 

The company also acknowledged that F-35 fighters, like other Western fighter aircraft, rely on US-secured data communication with Link-16 and GPS satellite navigation. 

Complete independence in this area, the company continued, "is not possible… not even with European systems," but noted that the F-35 still works without data links or satellite navigation. 

'Extremely difficult' to integrate new software into F-35s

Mark Cazalet, editor-in-chief at European Security and Defence Magazine, told Euronews Next he has not heard or seen any hard evidence that a kill switch exists but that it’s "not outside the realm of possibility" that measures to block aircraft software could be produced. 

Cazalet said the US "doesn't necessarily need" a kill switch on the F-35 to block the weapon’s use, the government could “simply withhold ammunition and spare parts”. 

To replace US control of the software would be “extremely difficult, if not impossible,” to integrate into their weaponry, Cazalet said. 

“The more relevant question for military planners is, can the US effectively prevent F-35s operated by other countries from being used, should it choose to do so?" Cazalet said. "Here the answer would seem to be mostly yes".

Countries block parts of ammunition or weapons on occasion, Cazalet continued. 

For example, Switzerland delayed the use of Ukraine’s Gepard anti-aircraft guns when they refused to export the 35 mm ammunition. The Germans had also shown some initial reluctance to export the Eurofighter Typhoon fighter jet to Turkey. 

F-35s 'can be used independently'

Euronews Next has contacted the US Department of National Defence (DND) and Lockheed Martin to confirm whether the US government has control over the software and hardware of the F-35 after the aircraft have been delivered but did not receive an immediate reply. 

A DND spokesperson confirmed to Canadian media that the US is in charge of both software and hardware upgrades for the planes and said that updates would continue for all nations that participated in their development. 

Euronews Next also asked Lockheed Martin whether they’d be able to give Germany and other European nations some assurances that these updates would continue. 

In response to Swiss media reports of similar kill switch concerns, Lockheed Martin published a post on their website on Monday titled 'Switzerland can use their F-35s independently'. 

The company says that blocking the F-35A fighter jets, through external interventions in the electronics, is not possible. 

"Switzerland does not need consent if it wants to use its weapon systems or guided missiles for its defence," the post reads. "It can do this autonomously, independently, and at any time".  

Countries like Switzerland can also decide when they want to upgrade the software of the fighter jets or not, and the missiles remain operational without these upgrades. 

If a country does want to upgrade, Lockheed said it sends a "mobile team" to carry out the updates with the respective government.