ANKARA, Turkey — A U.S. bill that would halt weapons sales to Turkey risks terminating all procurement deals between the two NATO allies, according to Turkish officials and procurement official. But a U.S. diplomatic source is downplaying the impact of the move, saying it would not be the end of a decades-long defense and security alliance.

Turkish Foreign Affairs Minister Mevlüt Cavuşoğlu said May 6 that the country would retaliate if the U.S. enacts the proposed law, calling the measures in the bill “wrong, illogical and not fitting between the NATO allies.”

“If the United States imposes sanctions on us or takes such a step, Turkey will absolutely retaliate. What needs to be done is the U.S. needs to let go of this,” he added.

Lawmakers in the U.S. House of Representatives on May 4 released details of a $717 billion annual defense policy bill, including a measure to temporarily halt weapons sales to Turkey.

“Turkey and the U.S. have been strong allies since the 1950s. In this period there have been ups and downs in arms trade and programs. None has completely derailed our military ties,” the U.S. diplomatic source said.

Washington imposed an arms embargo on Turkey following the Turkish invasion of the northern third of Cyprus in 1974. The invasion was in response to a Greek coup that aimed to annex Cyprus to Greece. The island has been divided along ethnic Turkish and Greek lines ever since.

If passed as part of the National Defense Authorization Act, the U.S. Defense Department would have to provide Congress with a report on the relationship between the NATO allies. Sales of major defense equipment would be blocked until the report is completed.

One immediate casualty could be the U.S.-led, multinational Joint Strike Fighter program in which Turkey is a partner. Turkey has committed to acquire a batch of more than 100 F-35 fighter aircraft.

The U.S. bill surfaced after Turkey announced in December that it would buy the Russian-made S-400 long-range air and anti-missile systems, the first such system to be deployed on NATO soil. Turkey says the S-400 deal, worth nearly $2.5 billion, is its sovereign decision.

Russia's S-400 air-defense systems ride through Red Square during the Victory Day military parade in Moscow on May 9, 2018. (Kirill Kudryavtsev/AFP via Getty Images)
Russia's S-400 air-defense systems ride through Red Square during the Victory Day military parade in Moscow on May 9, 2018. (Kirill Kudryavtsev/AFP via Getty Images)

The S-400 batteries will not be interoperable with U.S. and NATO assets in Turkey, but would instead operate as a stand-alone system. Çavuşoğlu said Turkey’s relations and agreements with Russia were not an alternative to its ties with the West and accused the U.S. of trying to control Turkey’s actions.

“Turkey is not a country under your orders, it is an independent country,” he said. “Speaking to such a country from above, dictating what it can and cannot buy, is not a correct approach and does not fit our alliance.”

U.S. Secretary of State Mike Pompeo in April told Çavuşoğlu that the United States was seriously concerned over Ankara’s decision to buy the Russian S-400 missile batteries.

In 2013, Turkey came under similar pressure from its NATO allies when it selected a Chinese manufacturer for its long-range air-defense system program. Ankara later dropped that decision.

In addition to the S-400 system, Turkey is in talks with the European group Eurosam, maker of the SAMP/T system, for a co-production deal to meet its longer-term surface-to-air missile requirements.

“If passed the U.S. bill has the potential to altogether alter Turkey’s Western paradigm,” according to a presidential aide in Ankara.

A senior procurement official said the bill would “kill all U.S.-Turkish procurement business in the several years ahead.”

“The U.S. is no longer a sole-source supplier of the kind of equipment we buy from foreign suppliers. It won’t have the leverage our American friends hope it will,” the official said.

A senior Turkish diplomat said the bill would push Turkey further into the Russian orbit. “There is a lot we could jointly do with the Russians … from engine technologies to satellites,” he said.

In April, a Russian aerospace official with Rostec said the company would propose to Turkey a joint engine development deal.

Analysts remain skeptical.

“I can hardly see the logic [behind the U.S. bill],” said Ahmet Doğan, managing editor at Sigma, a think tank in Ankara. “A NATO ally is proposing an arms embargo on Turkey because Turkey buys missile batteries from Russia, while several other NATO allies are queuing up to do defense business with Turkey.”