Hitachi Zosen Corporation
Hitachi Zosen is a Japanese manufacturing and engineering corporation with product divisions including environmental systems and industrial plants, precision machinery, machinery and process equipment, steel structures and construction machinery, marine and disaster prevention systems. (Company website)
Hitachi Zosen produces shield tunneling machines in its steel structures and construction machinery division: "We have delivered a number of shield tunneling machines to the United States, China, Korea, Republic of China, Singapore and Thailand including 4 machines for undersea tunnel across the Bosporus straits in Istanbul, Turkey" (Company website).
A Hitachi Zosen subsidiary lists Iran as a main exporting country for spare parts. (Hitachi-Zosen Plant Techno-Service Corp)