BERLIN (AP) -- Questions are mounting in Canada and in Europe over whether big-ticket purchases of high-end U.S. weaponry, such as the F-35 Joint Strike Fighter, are still a wise strategic choice for Western countries worried about their investment in U.S. defense technology.

In less than two months, U.S. President Donald Trump has upended decades of U.S. foreign policy. He has left NATO members questioning whether the U.S. will honor the alliance's commitment to defend each other if other European countries are attacked by Russia. He's also made repeat overtures to Russia and suspended most U.S. foreign aid.

And Pete Hegseth, Trump's defense secretary, last month told a gathering of European defense ministers "that stark strategic realities" prevent the U.S. from being primarily focused on the security of Europe.

That could impact foreign sales of the Lockheed Martin-produced F-35 and other advanced U.S. jets like the F-16. As the war in Ukraine continues into its fourth year, it's become clear that Eastern European NATO members still have vast stores of Soviet-era weapons in their stockpiles that were not interoperable with Western weaponry. A long-term plan to get all of NATO on similar platforms -- by replacing old Soviet-era jets with Western ones, particularly the F-16 and in some cases, the F-35 -- has gained momentum.

Some of the NATO countries are now re-thinking tying their defense to U.S.-made systems and potentially considering European jets like the Saab Gripen, Eurofighter Typhoon and Dassault Rafale instead.

In Canada, where Trump has launched a trade war and has threatened economic coercion to make it the 51st American state, new Prime Minister Mark Carney has asked Defense Minister Bill Blair to review its purchase of F-35s. Canada has been a partner with the U.S. in developing the F-35.

Blair will see if there are other options "given the changing environment," a defense spokesman said.

Carney on Tuesday announced a radar purchase from Australia worth Canadian $6 billion ($4.2 billion). The Over-the-Horizon Radar system will provide early warning radar coverage from the Canada-United States border into the Arctic, and officials said it would have a smaller footprint than a similar American system.

And in Portugal, the outgoing defense minister said in an interview with a Portuguese newspaper published last week that "recent positions" taken by the U.S. compelled a rethink about the purchase of F-35s because the U.S. has become unpredictable. Portugal is considering various options to replace its F-16s.

"You're not just buying an airplane, you're buying a relationship with the United States," said Winslow T. Wheeler, a longtime government watchdog who spent 30 years in the U.S. Congress working for Democrats and Republicans on national security and defense issues. "People in the past have not just welcomed but craved that kind of relationship."

The Netherlands and Norway have voiced recent support for the F-35 program in comments to the media.

"The F-35 is a vital component of our national defense capability, and the cooperation and dialogue with the United States continues to support the development and use of this high-end platform," Norwegian State Secretary Andreas Flåm said in a statement. "We expect this constructive cooperation to continue into the future."

The F-35 Joint Strike Fighter was designed to combine stealth, maneuverability and attack capabilities in a single aircraft. Each jet costs about $85 million (78 million euros), and the price jumps to $100 million (91 million euros) to $150 million (137 million euros) when supporting infrastructure and spare parts are included. About 1,100 have been produced to date for 16 military services across the globe.

The F-35B, a variant that can take off from ship decks vertically, is the latest model. It's the most expensive weapons system the U.S. has ever produced, with estimated lifetime costs now expected to top $1.7 trillion. One of the ways the program was counting on reducing those costs was by selling more aircraft to international customers.

But the Trump administration's recent pause on providing intelligence to Ukraine to force the country to negotiate with Russia has fueled fears that the U.S. may have similar ways to coerce them in a future fight -- such as by embedding a hypothetical "kill switch" in the F-35's millions of lines of programming.

In a statement, the Pentagon's F-35 Lightning II Joint Program Office on Tuesday vehemently rejected any notion that jets sold to allies could be remotely disabled.

"There is no kill switch. The F-35 was conceived, developed, and continues to be operated and sustained as a joint/coalition platform, built on strong partnerships with U.S. allies and partner nations across the globe," the office said in a statement. "The strength of the F-35 program lies in its global partnership, and we remain committed to providing all users with the full functionality and support they require."

But that's not the only way to impact an ally's program, Wheeler said. The F-35 requires constant U.S.-controlled tech upgrades to operate in combat. If a relationship with the U.S. soured and updates were delayed, it could make a jet, or even a fleet, inoperable, he said.

Lockheed Martin, in a statement Tuesday, said the company is committed to helping its customers "strengthen their airpower and security with the F-35."

"As part of our government contracts, we deliver all system infrastructure and data required for all F-35 customers to sustain the aircraft," the defense contractor said. "We remain committed to providing affordable and reliable sustainment services to our customers that enable them to complete their missions and come home safely."

The Saab Gripen, Eurofighter Typhoon and Dassault Rafale could see an increase in sales if other countries decide to forgo their F-35 purchases. But none of them have the stealth capabilities of the F-35.

The Swedish-made Saab Gripen is used by the militaries of Sweden, the Czech Republic, Hungary, South Africa,Brazil and Thailand. Conventional defense industry wisdom says it's significantly cheaper than the F-35, Wheeler said.

The Eurofighter Typhoon, a swing-role combat aircraft, is part of the British, German, Spanish and Italian forces. It's manufactured by a consortium of defense companies: Airbus, BAE Systems and Leonardo.

The French-built Dassault Rafale twin-jet fighter is used by the French Navy and the French Air and Space Force. The governments of Egypt, India, Qatar, Greece, Croatia, the United Arab Emirates, Serbia and Indonesia have all signed contracts for Rafales.

David Jordan, a senior lecturer in defense studies at King's College London and co-director of the Freeman Air and Space Institute, said that previously, European leaders felt it was easier and more cost-effective to lean on the U.S. defense industry -- and American taxpayers -- to get access to advanced weaponry. But the Trump administration's move away from Europe could be the turning point, Jordan said.

It would require the continent to pool its money and resources -- often a sticking point among the countries -- into research and development, manufacturing and logistics, but Jordan said it's possible within five to 10 years.

"The European defense industry is more than capable of building what it needs," Jordan said.

French President Emmanuel Macron is already ramping up his efforts to persuade France's allies to switch to European defense contractors and weapons systems, including French-built Rafale fighters.

"Those who buy the F-35 should be offered the Rafale. That's how we'll increase the pace," La Dépêche du Midi quoted Macron as saying during a press briefing Friday to journalists from regional French newspapers.

If the Europeans increase their production, it would greatly affect the bottom lines of Lockheed Martin and other U.S. defense companies. Jordan said U.S. defense contractors are likely concerned about Trump's next move.

"At what point will they say 'we don't like this, we're talking about risking billions of dollars here,'" Jordan said.

The White House did not respond to a request for comment Tuesday.

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Copp reported from Washington.