Tehran - Iranian lawmakers dressed in paramilitary uniforms chanted “Death to America” as they convened Tuesday for an open session of parliament after the White House designated Iran’s Revolutionary Guard a foreign terrorist organisation.

President Hassan Rouhani declared that the force’s popularity would only surge in the wake of the designation, saying guard members would be dearer “than any other time in the hearts of Iranian nation.”

Supreme Leader Ayatollah Ali Khamenei praised the guard and said America’s “evil designs would not harm” the force.

The move by Washington on Monday was an unprecedented declaration against a foreign government entity. It marks the first time the United States has designated an entire entity of another government as a terrorist organisation, placing a powerful and expansive armed force with vast economic resources that answers only to Iran’s supreme leader in the same category as Al Qaida and Daesh.

Iran’s rival, Saudi Arabia, welcomed the US decision, describing it as a “serious and practical step to combat terrorism.” A Foreign Ministry official said the designation “translates Saudi Arabia’s repeated demands for the international community to confront terrorism supported by Iran.”

Within hours of the Trump administration’s declaration, Iran’s Supreme National Security Council responded by designating the U.S. Central Command, also known as CENTCOM, and all its forces as terrorist, and labelling the US a “supporter of terrorism.”

In Tehran on Tuesday, many of the lawmakers wore the uniform of the guard in a show of support as they convened for a parliament session marking the National Day of the Revolutionary Guard, which follows the lunar calendar. This year it coincides with the April 9 holiday known as Nuclear Day.

Parliament Speaker Ali Larijani denounced the US decision as the “climax of stupidity and ignorance.” The Supreme National Security Council’s spokesman, Keivan Khosravi, said that going forward, “any unusual move by American forces in the region will be perceived as the behaviour by a terrorist group.” He did not elaborate.

Iranian newspapers carried reports of the US move along with bellicose commentary on their front pages.

The Guard-affiliated Javan daily said any attack on Revolutionary Guard bases and facilities will be “recognized as a right” for Iran to respond. The hard-line Kayhan newspaper said it gave Iranians “permission” to kill American military personnel.