The U.S. reportedly conducted a cyberattack on Iran following last month’s attack on Saudi oil facilities that affected 5% of world output. Both Washington and Riyadh blamed Iran for the missile and drone attack on the Aramco facilities despite claims of responsibility by Houthi rebels in Yemen.

Reuters, quoting two U.S. officials, reported the cyberattack affected Tehran’s propaganda machine. Iranian officials, however, denied any cyberattack had taken place.

“They must have dreamt it,” Iran’s Minister of Communications and Information Technology Mohammad Javad Azari-Jahromi told the Fars news agency.

Civil Defense Organization chief Gholam Reza Jalali said Iran has developed 200 new cyberdefense products and is equipped to fight off any cyberattacks.

The Pentagon declined comment, citing policy on operational security.

In 2010 the Stuxnet Worm was unleashed on Iranian nuclear facilities, resulting in 984 centrifuges breaking, about 30% of Iran’s uranium enriching resources. It was believed the attack came from a worker’s USB drive. National Security Agency whistleblower Edward Snowden said in 2013 the worm was designed by the U.S. and Israel although that never has been any concrete evidence that was the case.

The U.S., Saudi Arabia, Britain, France and Germany publicly blamed Iran for the Sept. 14 attack, which targeted the world’s largest oil processing plant in Abqaiq and the Saudi Arabia’s second largest oil field at Khurais. Production levels have since returned to normal. The Pentagon sent equipment and thousands of additional troops to shore up Saudi defenses in response.

Tensions in the region have been escalating since President Trump pulled out of the Iran nuclear deal, and Tehran resumed enriching uranium.

Iran downed a U.S. drone earlier this year and there have been attacks on oil tankers in the Persian Gulf. Iranian President Hassan Rouhani accused an unspecified government of being responsible for an attack on an Iranian tanker in the Red Sea and promised retaliation. Last month, Iran urged the West the leave the Persian Gulf to allow countries in the region to take responsibility for security in the area.

The U.S. also has tightened sanctions on Iran, an action Rouhani has labeled “economic terrorism” but vowed the sanctions will not bring Tehran to its knees. Rather, he said, the sanctions are making Iran more self-sufficient.