Iran's first Supreme Leader Ayatollah Ali Khameini broking down and cried during the "million-strong" funeral of slain Iranian General Qasem Soleimani on Monday.

During the funeral on Monday, the Iranian Supreme leader was seen weeping. The usually reserved and dignified Khameini wept openly standing near the remains of his most loved General.

"Oh Allah, they are in need of your mercy, and you are exalted above punishing your servants, Khameini said during the televised mass prayer at the funeral.

Soleimani, a respected military general, played a crucial role in the overseas clandestine and military operations as the head of the Revolutionary Guards' Quds Force. He was killed on Friday in a US drone attack that targeted his convoy at the Baghdad airport. The US drone strike was carried out following the attack outside the US Embassy in Baghdad.

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Iran has threatened the US with dire consequences for the death of the much-respected military leader. His funeral procession saw millions of Iranians taking to the streets. The people's participation was something unprecedented in Iranian history and surpassed the procession that turned up for the funeral of the Islamic Republic's founder, Ayatollah Ruhollah Khomeini in 1989.

Soleimani's son, the new chief of Quds force Esmail Qaani and Iranian president Hassan Rouhani were also present at the funeral in Tehran. Mourners prayed together with Khameini amidst anti-America sloganeering.

Soleimani's body was laid to rest at Tehran's famed Musalla mosque as the revolutionary leader did before him.

In Iran, many view Soleimani as a national hero, but he also has been accused of atrocities that were carried out by Iran's proxy militias operating largely in Iraq, Syria, and Yemen.

At the funeral, Soleimani's daughter warned families of American soldiers that they will not be able to enjoy calm and peace anymore as their loved ones will be targeted by the Iranian resistance forces, reported Fars News Agency - a "semi-official" news agency of the Government of Iran.

Zeinab Soleimani addressing President Trump said, "Hey mad Trump, the Gambler! You are the symbol of ignorance and a plaything in the hands of the Zionists. You should not think that everything has ended with my father's martyrdom."