"The United States remains concerned with Iran's development of space launch vehicles, which pose a significant proliferation concern," a State Department spokesperson said after Iran announced it had sent three research cargo units into space.

The space launch vehicles "incorporate technologies that are virtually identical to, and interchangeable with, those used in ballistic missiles, including longer-range systems," the spokesperson said.

The spokesperson contended that Iran's space launches also violate UN Security Council Resolution 2231, which blessed a 2015 nuclear deal and called upon Iran not to carry out work on ballistic missiles with the potential to carry nuclear warheads.

Former president Donald Trump pulled the United States out of the deal three years later and imposed sweeping sanctions.

President Joe Biden backs a return to the talks, with US negotiator Rob Malley again in Vienna for European-brokered negotiations on reviving the so-called Joint Comprehensive Plan of Action (JCPOA).

"Iran's nuclear program was effectively constrained by the JCPOA," the spokesperson said.

"The previous administration released them from those constraints, making all the other concerns we have about Iranian policy, including their provocative ballistic missile program, still more dangerous.

"That is why we are seeking a mutual return to full compliance with the deal."

The Biden administration has been disappointed by the pace of the talks, with Iran electing a new hardline president and demanding a sweeping lift of sanctions beyond the offer of Washington.

Since tensions with Iran under the Trump administration, analysts say Tehran has made major advances in its missile program, as demonstrated in a 2020 air strike on a base in Iraq used by US forces.