After four years of planning, TSMC is now finally going to make older iPhone processors in the US, but it's not and never will be a true return to American manufacturing.

Taiwan Semiconductor Manufacturing Co has begun producing advanced four-nanometer chips for U.S. customers in Arizona, Commerce Secretary Gina Raimondo told Reuters, a milestone in the Biden administration's semiconductor efforts.

Apple is already testing the initial batch of processors produced for its devices by TSMC Arizona, reports Nikkei Asia. To begin with, the tests intend to compare the Arizona output to see if the quality is similar to chips produced in TSMC’s cutting-edge fabs in Taiwan.

In a recent interview with , US Commerce Secretary Gina Raimondo announced that TSMC has initiated production of 4nm process technology chips at its Arizona facility in recent weeks, serving American customers.

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TSMC's chip foundry in Arizona is not just making one Apple chip, as a second Apple design is reportedly now in production at the facility.

The Arizona fab is a key move to strengthen U.S. semiconductor supply chains as competition in the industry heats up globally. The Arizona facility has led the transition, but other tech giants, such as AMD ( AMD,