It's time for the United States to hold Iran accountable.

Iran's military said Sunday that it has launched several missiles into eastern Syria, targeting Islamic State fighters in retaliation for the twin attacks that rocked Tehran on June 7.

The strikes are the first time Iran has fired missiles at another country in three decades and represent a major escalation of Iran's role in the war in Syria.

Islamic Revolutionary Guard Corps (IRGC) said on its official news website, Sepah News, that several "ground-to-ground, mid-range missiles" were fired from bases in Kermanshah province, western Iran.

The operation "targeted Takfiri forces in the Deir Ezzor region in Eastern Syria."

Iran's Revolutionary Guard uses the term Takfiri to describe ISIS.

Six assailants killed at least 16 people at Iran's Parliament building and a shrine dedicated to the republic's revolutionary founder Ayatollah Khomeini. The attacks marked the the first time that ISIS, a Sunni Muslim group fighting Iranian-backed militias in Syria, has claimed responsibility for an attack in Iran.

Iran backs Syrian President Bashar al-Assad in his fight against anti-government rebel groups and ISIS, which is primarily based in the Syrian city of Raqqa.

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