Iran has been frequently accused by the US government and its allies of launching cyber attacks against the US government and its entities. The US claimed that a unit under the command of Iran's elite Revolutionary Guards undertakes all these attacks.
These alleged cyber attacks by Iran, majority of which were unsubstantiated, however did not do as much damage as the alleged cyber attack by the US and its allies with the cyber worm Stuxnet on Iran's nuclear facility which apparently destroyed over 1,000 nuclear centrifuges setting back the country's atomic program.
Back to the present day. BBC News on 23 June 2019 reported that the US launched a cyber attack on 20 June 2019 against Iran disabling the network system controlling the country's rocket and missile launchers. The attack was in retaliation for the shooting down of a US drone as well as attacks on oil tankers that the US has blamed Iran for.
Ironically, BBC News also quoted a US Department for Homeland Security warning issued on 23 June 2019 that Iran was stepping up its own cyber-attacks on the US. The director of the Cybersecurity and Infrastructure Security Agency apparently was quoted to have said that "malicious cyber-activity" was being directed at US industries and government agencies by "Iranian regime actors and their proxies".
No details, however, were provided as to how the US detected the malicious cyberactivity and the industries that Iran is allegedly targeting.
Present action of the US government is akin to the story of the boy who cried wolf except that in this case, the boy cried wolf to conceal his intention of entrapping the wolf.