The United States set an important precedent on Monday for other states seeking to curb the Islamic Republic of Iran’s malign activities: It designated the country’s notorious Islamic Revolutionary Guard Corps and its Quds Force, the extraterritorial branch of the IRGC, as a terrorist organization.

Specifically, the designation means that the United States will impose direct sanctions on the IRGC as part of the “maximum pressure” campaign against Iran that saw America withdrawing from the 2015 nuclear deal and the ensuing reimposition of sanctions.

Because of the IRGC’s significant influence in Iran’s banking and shipping industries, the designation makes it easier to sanction the European Union and other entities still doing business with the Islamic Republic. It is estimated that the IRGC controls one-sixth of Iran’s economy and benefited significantly from the lifting of sanctions on Iran.

Whereas the European Union has blacklisted only some individuals in the IRGC—entertaining the illusion that some factions in the organization can be reasoned with—the United States has taken the only logical step and has put the entire organization on its terrorist list.

Just as it is impossible to separate Hezbollah’s political wing from its military wing, it’s impossible to separate the IRGC from the regime, the Quds Force from the IRGC, or draw other artificial distinctions that prevent the European Union from taking meaningful steps against Iran’s reign of terror.

Since its foundation, the IRGC has overseen a terror apparatus that has assassinated opposition activists, intellectuals and journalists within Iran, and that has been involved in torture and egregious human-rights abuses.

Beginning in the 1980s, the IRGC was employed to persecute minorities and suppress dissidents inside the Islamic Republic. The IRGC was instrumental in putting down the 1999 student revolt—a decision supported by now-President Hassan Rouhani, who was then the Secretary of the Supreme National Security Council.

The IRGC has served as a primary vehicle for accomplishing Tehran’s illicit nuclear and non-nuclear ambitions, as well as exporting the Islamic Revolution’s extremist ideology. The organization, numbering more than 120,000 members, is the largest terror organization in the world—even bigger than the combined membership of the Taliban and Al-Qaeda.

Iran has committed innumerable terrorist attacks through proxy organizations, such as Hamas in Gaza and Hezbollah in Lebanon, which in turn execute terror attacks to advance Iranian interests.

For example, the Iranian-backed Hezbollah helped the IRGC carry out the 1983 attack on the U.S. Marines barracks in Beirut, killing 238 American soldiers, and the 1996 bombing of Khobar Towers in Saudi Arabia, killing 19 American soldiers. In 2011, an Iranian agent was convicted of attempting to assassinate then-Saudi Ambassador to the United States Adel al-Jubeir at a Washington restaurant. The plot was directed by elements of the Iranian regime and, specifically, by senior members of the Quds Force.

The use of terrorism against its rivals is an important element of Iran’s military strategy, helping to create fear and deterrence among Tehran’s enemies. Aid to terrorist organizations serves Iran’s desire to shape the geopolitics of the region—in Lebanon, Syria, Iraq, Yemen, Bahrain, the Palestinian territories, even Saudi Arabia. The IRGC was instrumental in the survival of the regime of Syrian dictator Bashar Assad. Iran has been directly complicit in the slaughter of innocent civilians carried out by either Iranian-controlled Shi’ite militias or Assad’s forces. The Islamic Republic’s regional clout has also been boosted through having a presence in Iraq and Yemen.

It is truly shameful that European states continue to evade U.S. sanctions as the regime in Tehran continues its reign of terror at the expense of its own people and the stability of the entire region.

Given the havoc wreaked by the IRGC, the European Union and other actors must understand that they cannot stabilize the Middle East, nor protect their own security interests, without first weakening the IRGC. And the key to weakening the IRGC is to attack its financial empire and, in return, to support the United States in its hard-hitting sanctions regime against Iran.

Josh Block is CEO and president of the Israel Project.