President Recep Tayyip Erdogan visited Moscow on his first trip abroad after the March 31 elections and, on the flight back home, told journalists traveling with him that the delivery of the Russian S-400 air defense systems to Turkey could occur sooner than July, as scheduled.

No crisis between Turkey and the Western alliance has been as predictable as the one over the S-400s. It’s because US sanctions mechanisms against countries that purchase significant weaponry from Russia cannot be stopped; once Turkey receives the strategic S-400 air defense systems, the sanctions will be activated.

Turkey would be subject to penalties under the 2017 Countering America’s Adversaries Through Sanctions Act, in addition to a separate measures that would bar it from receiving F-35 stealth fighters as part of a joint production program, in which it is both a coproducer and buyer. The worries over Turkey’s acquisition of both the F-35s and the S-400s stem from the risk that the radars of the Russian systems could compromise the “stealth” capabilities of the fifth-generation fighter. Thus, a country’s simultaneous possession of the F-35 jets and the S-400 systems is seen as unacceptable in terms of the security of the F-35 project.

The Turkish public perceives the S-400 crisis as a bilateral issue between Ankara and Washington. But if the security of the F-35 project is at stake, the issue goes beyond the United States, the principal manufacturer of the jet, meaning that other coproducers and buyers could have a potential problem with Turkey as well. Australia, Canada, Denmark, Italy, the Netherlands, Norway and the United Kingdom are the other coproducers of the costly aircraft, whose prices range from $90 million to $115 million, depending on the model. Israel, Japan and South Korea are buyers through direct military sales, with Finland and Belgium also considering purchasing the jet to modernize their existing air fleets.