“They try hard but have not carried out a successful attack,” an Iranian minister tweeted on Monday.

By Batya Jerenberg, World Israel News

The U.S. attempt last week to attack Iranian military computer systems did not succeed, Mohammad Javad Azari Jahromi, Iran’s minister for Information and Communications Technology, said.

“They try hard but have not carried out a successful attack,” he tweeted on Monday..

Calling such attempts “cyber-terrorism,” he also touted his country’s cyber defenses, saying, “Last year we neutralized 33 million attacks with the (national) firewall.”

Two American officials, however, told The Associated Press that the attack successfully targeted Iran’s rocket and missile launch systems. It specifically hacked those belonging to Iran’s Islamic Revolutionary Guard Corps (IRGC), which has been designated as a foreign terrorist group by the American administration, they said.

The officials spoke anonymously as they were not authorized to discuss the operation.

President Donald Trump initially approved a military strike on three Iranian targets in retaliation for the shooting down of a U.S. drone over the Strait of Hormuz on Thursday, but then pulled back, citing too great a loss of life as one reason. He gave the go-ahead for the cyber strike instead, the officials said.

The Americans said the drone was in international airspace when the Iranians hit it, while Tehran claimed that it had crossed the border into their country first.

“This firm response can be repeated, and the enemy knows it,” Iranian naval commander Admiral Hossein Khanzadi warned on Monday, Iran’s Tasnim news agency reported.

According to cybersecurity companies that track such activity, both Iran and the U.S. have upped the ante in their hacking attempts. The Iranians have targeted government agencies and the oil, gas and finance industries, the companies said.

Without confirming any specific attempted attacks, the American National Security Agency (NSA) said in a statement to AP on Friday that “there have been serious issues with malicious Iranian cyber actions in the past.”

“In these times of heightened tensions, it is appropriate for everyone to be alert to signs of Iranian aggression in cyberspace and ensure appropriate defenses are in place,” the statement added.