Iranian President Hassan Rouhani on Monday commemorated the 40th anniversary of the 1979 revolution, calling it an event that saved the country “from tyranny, colonisation and dependence”, reported Al Jazeera. Hundreds of thousands of Iranians celebrated the anniversary all over the country.

The landmark revolution led to the ouster of United States-backed ruler Shah Mohammad Reza Pahlavi on February 11, 1979, and the country became the Islamic Republic of Iran under leadership of Ayatollah Ruhollah Khomeini. The Shah dynasty collapsed after 10 days of violent protests.

Demonstrators braved rain and snow on Monday, carrying Iranian flags and chanted slogans such as “Death to Israel, death to America”. Security was tightened across the country.

A resolution was read out, proclaiming “unquestioning obedience to the Supreme Leader Ayatollah Ali Khamenei” and calling US President Donald Trump an idiot, reported AFP.

Rouhani, in a speech at Tehran’s Azadi Square, said renewed sanctions by the United States would not break the Islamic Republic, Reuters reported. “We will not let America become victorious...” he said. “Iranian people have and will have some economic difficulties but we will overcome the problems by helping each other.”

Rouhani pledged to pursue Iran’s missile programme to defend the country from external threats. “We have not asked, and will never ask for permission in developing our missile arsenal as we continue to pursue our path to military might,” he added.

A nuclear deal signed by the five permanent members of the United Nations, Germany, the European Union and Iran in 2015 lifted crippling sanctions imposed on Tehran after the revolution. However, US President Donald Trump pulled the US out of the agreement in May.