Iranian President Hasan Rouhani and Iran’s supreme leader Ayatollah Ali Khamenei. (Photo: Office of the Supreme Leader)

(CNSNews.com) – A declaration by Iran of plans to develop nuclear-powered vessels – in response to legislation extending U.S. sanctions – is not a violation of the nuclear deal, White House press secretary Josh Earnest said Tuesday.

“The announcement from the Iranians today does not run counter to the international agreement to prevent Iran from obtaining a nuclear weapon,” he told a news briefing.

Iran has made such announcements before, and some experts have treated them dismissively.

At the same time, however, nuclear reactors powering ships or submarines are in some cases fueled with uranium enriched to more than 90 percent. The nuclear deal known as the Joint Comprehensive Plan of Action (JCPOA) permits Iran to enrich uranium to no more than 3.67 percent.

In a letter to Atomic Energy Organization of Iran head Ali Akbar Salehi, President Hasan Rouhani instructed the AEOI to begin planning to develop “nuclear propulsion for use in the field of maritime transportation” as well as the production of fuel for that purpose.

Without indicating whether the plans would entail surface vessels or submarines, Rouhani said the work should be performed within the framework of Iran’s “peaceful nuclear program” and its international obligations.

He made clear that the steps were Iran’s response to the recent passage by Congress of legislation extending the Iran Sanctions Act (ISA) by ten years. Separately, Rouhani instructed Foreign Minister Javad Zarif to make formal complaints through established mechanisms about the purported JCPOA violation.

The White House says the extension does not violate the JCPOA (since non-nuclear sanctions in the ISA were not covered in the nuclear deal in any case, and the ISA’s nuclear sanctions will continue to be waived.) President Obama is expected to sign the measure into law soon.

Earnest said the JCPOA gives the U.S. and partners the ability to watch Iran’s program and verify its ongoing compliance with the agreement.

“Our expectation is that as they undertake these kind of research and development efforts that they will do so consistent with their international obligations,” he said.

State Department spokesman John Kirby – a retired U.S. Navy admiral – told reporters that the work Iran says it plans to do “is a massive undertaking for any nation and is likely decades in the effort to begin to realize it.”

In 2012, Iranian Navy officials announced that initial steps had been taken to develop nuclear-powered submarines, an achievement that only the five permanent U.N. Security Council members – and, recently, India – have made to date.

Some experts discounted Iran’s ability to do so, and some suggested it was preparing the way to justify the need to enrich uranium to levels much higher than otherwise required for the supposedly peaceful program it professed to have.

Nuclear scientists say the U.S. and Britain use high-enriched uranium (HEU) enriched to more than 90 percent – weapons-grade – for their naval vessels’ nuclear reactors, while Russia uses more than 20 percent HEU. France and China use low-enriched uranium in theirs.

According to International Atomic Energy Agency (IAEA) guidelines, uranium enriched more than 20 percent is HEU. Under the JCPOA Iran is allowed to enrich uranium to no more than 3.67 percent, for a period of at least 15 years.