Albania severed diplomatic relations with Iran on Wednesday and ordered Iranian diplomats and embassy staff to leave within 24 hours, saying a probe had found the Islamic Republic was behind a cyberattack on the country in July.

“The government has decided with immediate effect to end diplomatic relations with the Islamic Republic of Iran,” Prime Minister Edi Rama said in a video statement sent to the media.

“This extreme response … is fully proportionate to the gravity and risk of the cyberattack that threatened to paralyze public services, erase digital systems and hack into state records, steal government intranet electronic communication and stir chaos and insecurity in the country,” Rama said.

There was no immediate comment from the Iranian Embassy in Tirana.

The United States also said it concluded after weeks of investigation that Iran was behind the “reckless and irresponsible” July 15 cyberattack and said it would support its 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,” the White House National Security Council said in a statement.

The two countries have had tense relations since 2014, when Albania accepted some 3,000 members of the exiled opposition group People’s Mujahideen Organization of Iran, also known by its Farsi name Mujahideen-e-Khalq, who have settled in a camp near Durres, the country’s main port.

Albania has previously said it had foiled a number of planned attacks by Iranian agents against the Iranian opposition group.

“The in-depth investigation provided us with indisputable evidence that the cyberattack against our country was orchestrated and sponsored by the Islamic Republic of Iran through the engagement of four groups that enacted the aggression,” Rama said.