State Department spokesperson Marie Harf said she was "perplexed" by a New York Times story Tuesday on Iran’s 20 percent increase in nuclear fuel over the past 18 months.

The United States has been in negotiations with Iran for a final deal about their nuclear program. The International Atomic Energy Agency issued a report on Friday that documented an increase of Iran’s nuclear fuel stockpile.

A reporter asked Harf if Iran’s increased stockpiles has complicated the current negotiations.

"Not at all. Our team read that story this morning and was quite frankly perplexed because the main contentions of it are totally inaccurate," Harf said.

Harf explained why she felt that way.

"First, the notion in the story that western officials or U.S. officials involved were unaware of this issue or not understanding of what this entails is just absurd," Harf said. "Under the JPOA (Joint Plan of Action), Iran can fluctuate its numbers in terms of their stockpile. They can go up and down as long as at the end of fixed date they are back down below a number."

Iran’s increase in its nuclear stockpile during the negotiations goes against what White House Press Secretary Josh Earnest said during a White House briefing on March 2.

"So what we also know is that Iran has decided to engage in a set of serious negotiations, that previously Iran had just used diplomatic negotiations as cover to try to make progress on their nuclear program," Earnest said. "But in the context of these talks, we’ve actually succeeded in not just halting Iran’s progress as it relates to their nuclear program but actually rolling it back in several key areas, including reducing and eliminating their stockpile of highly enriched uranium. So I think the evidence indicates that this sanctions regime has been effective."

Harf said that this is not a concern because Iran agreed to reduce their stockpile when the agreement gets implemented.

"What matters is that they [Iran] have committed already, and we said publicly to reducing their stockpile whenever this implemented 300 kilograms," Harf said. "The notion that this is some big issue of concern of negotiation is more manufacturing a controversy than actual reality. Everyone who read that story this morning was totally perplexed by it."

The Institute for Science and International Security analyzed the question of whether Iran could meet its obligations regarding 5 percent low enriched uranium, and authors David Albright and Serene Kelleher-Vergantini assessed that "Iran has fallen behind in its pledge to convert its newly produced LEU hexafluoride into oxide form. There are legitimate questions about whether Iran can produce all the requisite LEU oxide … By the end of June, in order to meet its commitment under the JPA, Iran must finish converting the 2,720 kg of LEU into oxide and introduce into the EUPP and convert into oxide, 1,106 kg of 3.5 percent LEU hexafluoride produced over the last several months (plus the few hundred kilograms of LEU to be produced in late May and June 2015). Thus, Iran has clearly fallen behind in its pledge under the JPA."