After years shunning Iran, Western businesses are bursting through the country’s doors—but U.S. companies are noticeably absent.

Dozens of development projects and deals have been hammered out since Iran’s nuclear accord with world powers in 2015 lifted a range of sanctions. Among them, France’s Peugeot and Renault SA are building cars. The U.K.’s Vodafone Group PLC is teaming up with an Iranian firm to build up network infrastructure. Major oil companies including Royal Dutch Shell PLC have signed provisional agreements to develop energy resources. And infrastructure giants, including Germany’s Siemens AG, have entered into agreements for large projects.

Chicago-based Boeing Co. last year got the go-ahead to sell 80 aircraft valued at $16.6 billion to Iran. But for the most part, deals involving U.S. businesses are few and far between.