Albania has ordered Iranian officials out of the country and severed diplomatic relations with Tehran following an investigation into a cyberattack that it concluded was Iranian "state aggression" when it hit the Balkan country in July.
The move sparked a quick expression of support from Washington, a NATO ally, along with a U.S. threat of other punitive moves against Tehran, which called the action ill-considered and short-sighted.
On September 7, Prime Minister Edi Rama announced the expulsion of all Iranian diplomats and embassy staff and gave them 24 hours to leave.
Rama's official website described "irrefutable" evidence that Tehran had backed "the act of a serious cyberattack against the digital infrastructure of the government of the Republic of Albania."
"The government has decided, with immediate effect, to end diplomatic relations with the Islamic Republic of Iran," Rama said in a video statement on his website.
Rama said Tirana had already informed Iran of its decision in a diplomatic note to the Iranian Embassy.
It also said it had shared its findings with fellow NATO members.
Rama said the "extreme measure" was "not at all desired but completely forced...[and] in full proportion to the seriousness and dangerousness of the cyberattack, which threatened to paralyze public services, delete systems, and steal state data, steal electronic communications within the government system, and fuel insecurity and chaos in the country."
The Iranian Foreign Ministry denied Tehran was behind any cyberattack on Albanian government websites.
"This was an ill-considered and hasty decision based on unfounded insinuations," the ministry said in statement.
It said Iran is itself a victim of cyberattacks on critical infrastructure.
The White House later condemned the alleged Iranian actions and warned of "further action" for an "unprecedented" cyberattack on a NATO ally.
"The United States will take further action to hold Iran accountable for actions that threaten the security of a U.S. ally and set a troubling precedent for cyberspace," National Security Council spokeswoman Adrienne Watson said in a statement.
Britain said its National Cybersecurity Center had determined Iranian state-linked actors were "almost certainly responsible" for the cyberattack against the Albanian government.
"Iran's reckless actions showed a blatant disregard for the Albanian people, severely restricting their ability to access essential public services," British Foreign Secretary James Cleverly said in a statement, adding that Britain joins Albania and other allies "in exposing Iran's unacceptable actions."
The United States is already engaged in bitter indirect talks with Iran over international efforts to revive a frayed seven-year-old agreement to exchange curbs on Iran's nuclear activities for sanctions relief that Washington abandoned four years ago.
Tirana and Tehran's relations dramatically worsened after Albanian authorities agreed at the request of the United States in 2013 to accept around 3,000 members of an exile group known as the Mujahedin-e Khalk (MEK), whom Iranian officials regard as terrorists.
A team of U.S. cyberexperts from the FBI were recently sent to neighboring Montenegro over what officials of that Balkan NATO member called a massive and coordinated cyberattack on its government and services.
A source from Montenegro's National Security Agency initially suggested Russian security services were suspected, although a Cuban group later claimed it was behind the attack.