The State Department struggled on Wednesday to answer a flurry of questions from reporters regarding recent reports that Iran’s nuclear stockpile has significantly expanded in recent months, constituting a potential violation of past agreements made with the United States.

For the second day in a row, State Department Spokeswoman Marie Harf faced pointed questions about Iran’s growing nuclear stockpile for around 15 minutes.

The questions followed strong denials by the Obama administration on Tuesday regarding a New York Times report disclosing that Iran’s stockpiles of nuclear materials had grown 20 percent during the last 18 months.

Such a growth in Iran’s nuclear stockpile—which was initially discovered by United Nations inspectors—is viewed by some as a violation of an interim nuclear deal struck with Western powers in 2013.

The Obama administration has repeatedly touted that deal as completely freezing the most controversial aspects of the Islamic Republic’s nuclear program.

After claiming on Tuesday that the administration was “totally perplexed” by the “inaccurate” Times report, Harf went on to engage in a lengthy Twitter debate about the topic on Wednesday morning.

Harf singled out the story’s author, Times reporter David Sanger, and criticized the Washington Free Beacon for reporting on her initial exchange with State Department reporters.

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