The equipment involves centrifuges known as IR-2s, described as a better component than the Pakistan-designed model Iran had been using in enriching nuclear fuel.
Debate in Washington is said to likely center on whether a recent National Intelligence Estimate accurately portrayed Tehran's progress toward the ability to build a nuclear weapon.
U.S. National Intelligence Director Mike McConnell told Congress that he regretted how the National Intelligence Estimate had been written, which some said left the impression that Iran was no longer seeking a nuclear weapons capability.
Iran's refusal to halt uranium enrichment, he said, meant it still posed a potential nuclear threat.
Iranian officials say the program is for peaceful purposes.