BAGHDAD -- BAGHDAD -- Thousands took to the streets of Baghdad for the funeral procession of Iran's top general Saturday after he was killed in a U.S. airstrike, as the region braced for the Islamic Republic to fulfil its vows of revenge.

The day of mourning in the Iraqi capital ended Saturday evening with a series of rockets that were launched and fell inside or near the Green Zone, which houses government offices and foreign embassies, including the U.S. Embassy.

Iran has vowed harsh retaliation for the U.S. airstrike ordered early Friday by U.S. President Donald Trump that killed Gen. Qassem Soleimani, the head of Iran's elite Quds Force and mastermind of its regional security strategy, and several senior Iraqi militants. The attack has caused regional tensions to soar, raising fears of an all-out war, and tested the U.S. alliance with Iraq.

Trump, meanwhile, warned that the U.S. too was ready to respond if Tehran strikes back. that he U.S. had already "targeted 52 Iranian sites (representing the 52 American hostages taken by Iran many years ago), some at a very high level & important to Iran & the Iranian culture."

Trump did not identify the targets but added that they would be "HIT VERY FAST AND VERY HARD."

Trump says he ordered the strike, a high-risk decision that was made without consulting Congress or U.S. allies, to prevent a conflict. U.S. officials say Soleimani was plotting a series of attacks that endangered American troops and officials, without providing evidence.

Soleimani was the architect of Iran's regional policy of mobilizing militias across Iraq, Syria and Lebanon, including in the war against the Islamic State group. He was also blamed for attacks on U.S. troops and American allies going back decades.

Though it's unclear how or when Iran may respond, any retaliation was likely to come after three days of mourning declared in both Iran and Iraq. All eyes were on Iraq, where America and Iran have competed for influence since the 2003 U.S.-led invasion.

After the airstrike early Friday, the U.S.-led coalition has scaled back operations and boosted "security and defensive measures" at bases hosting coalition forces in Iraq, a coalition official said on the condition of anonymity according to regulations. Meanwhile, the U.S. has dispatched another 3,000 troops to neighbouring Kuwait, the latest in a series of deployments in recent months as the standoff with Iran has worsened.

In a thinly veiled threat, one of the Iran-backed militia, Asaib Ahl al-Haq, or League of the Righteous, called on Iraqi security forces to stay at least 1,000 metres (0.6 miles) away from U.S. bases starting Sunday night. However, US troops are invariably based in Iraqi military posts alongside local forces.

"The leaders of the security forces should protect their fighters and not allow them to become human shields to the occupying Crusaders," the warning statement said.

By Saturday evening, as the funeral processions were still taking place, a series of rocket attacks on bases that house U.S. forces were launched. A Katyusha rocket that fell inside a square less than a kilometre from the U.S. Embassy, according an Iraqi security official who spoke on condition of anonymity because he was not authorized to speak to reporters. The U.S.-led coalition confirmed the attack, saying indirect fire landed outside of its facilities. No troops were hurt.

Rockets also landed in the vicinity of Balad air base, about 40 miles north of Baghdad, the coalition said, adding that no troops were hurt. Earlier an Iraqi official said three rockets fell in a farm area outside the base.

"We have increased security and defensive measures at the Iraqi bases that host (anti-Islamic State) Coalition troops," said spokesman Col. Myles B. Caggins, who said the troops have come under 13 different attacks throughout Iraq in the past two months.

Another rocket in Baghdad landed about 500 metres from As-Salam palace where the Iraqi President Barham Salih normally stays in Jadriya, a neighbourhood adjacent to the Green Zone, the Iraqi official said.

Meanwhile, a spokesman for the Iraqi armed forces said Saturday the movement of coalition forces, including U.S. troops, in the air and on the ground will be restricted, conditioned on receiving approval from Prime Minister Adel Abdul-Mahdi, the commander in chief of the armed forces.

It was not immediately clear what the new restrictions would mean, given that coalition troops were already subject to limitations and had to co-ordinate with the Joint Operation Command of top Iraqi military commanders.

Iraq's government, which is closely allied with Iran, condemned the airstrike that killed Soleimani, calling it an attack on its national sovereignty. Parliament is meeting for an emergency session Sunday, and the government has come under mounting pressure to expel the 5,200 American troops who are based in the country to help prevent a resurgence of the Islamic State group.

Also Saturday, NATO temporarily suspended all training activities in Iraq due to safety concerns, Canadian Defence Minister Harjit Sajjan said.

Amid the rising tension, the funeral procession for Soleimani and his aides lasted all of Saturday, moving from Baghdad to two of Shiite Islam's holiest cities, Najaf and Karbala.

In Baghdad, thousands of mourners, mostly men in black military fatigues, carried Iraqi flags and the flags of Iran-backed militias that are fiercely loyal to Soleimani at Saturday's ceremony. They were also grieving for Abu Mahdi al-Muhandis, a senior Iraqi militia commander who was killed in the same strike.

The mourners, many of them in tears, chanted "No, No, America," and "Death to America, death to Israel." Mohammed Fadl, a mourner dressed in black, said the funeral is an expression of loyalty to the slain leaders. "It is a painful strike, but it will not shake us," he said.

Helicopters hovered over the procession, which was attended by Abdul-Mahdi and leaders of Iran-backed militias. As the procession later made its way to the holy city of Karbala, the mourners raised red flags associated with unjust bloodshed and revenge.

The slain Iraqi militants will be buried in Najaf, while Soleimani's remains will be taken to Iran. More funeral services will be held for Soleimani in Iran on Sunday and Monday, before his body is laid to rest in his hometown of Kerman.

The U.S. has ordered all citizens to leave Iraq and temporarily closed its embassy in Baghdad, where Iran-backed militiamen and their supporters staged two days of violent protests in which they breached the compound. Britain and France have warned their citizens to avoid or strictly limit travel in Iraq.

No one was hurt in the embassy protests, which came in response to U.S. airstrikes that killed 25 Iran-backed militiamen in Iraq and Syria. The U.S. blamed the militia for a rocket attack that killed a U.S. contractor in northern Iraq.

Tensions between the U.S. and Iran have steadily intensified since Trump's decision to withdraw from the 2015 nuclear deal and restore crippling sanctions that have devastated Iran's economy and contributed to recent protests there in which hundreds were reportedly killed.

In an apparent effort to defuse tensions, Qatar's foreign minister, Sheikh Mohammed bin Abdulrahman Al Thani, made an unplanned trip to Iran where he met with Rouhani and other senior officials.

Qatar hosts American forces at the Al-Udeid Air Base and shares a massive offshore oil and gas field with Iran.

Secretary of State Mike Pompeo spoke with various world leaders including Iraqi President Barham Salih, Turkish Foreign Minister Mevlut Cavusoglu and Abu Dhabi Crown Prince Sheikh Mohammed bin Zayed Al Nahyan, of the United Arab Emirates. "I reaffirmed that the U.S. remains committed to de-escalation," Pompeo tweeted.

In Tehran, Iranian President Hassan Rouhani visited Soleimani's home to express his condolences. "The Americans did not realize what a great mistake they made," Rouhani said.

As threats of revenge against the U.S. loomed, major streets in Iran were filled with billboards and images of Soleimani, who was widely seen as a national icon and a hero of the so-called Axis of Resistance against Western hegemony.

"I don't think there will be a war, but we must get his revenge," said Hojjat Sanieefar. America "can't hit and run anymore."

Another man, who only identified himself as Amir, was worried.

"If there is a war, I am 100% sure it will not be to our betterment. The situation will certainly get worse," he said.

In a sign of his regional reach, supporters in Lebanon hung billboards commemorating Soleimani in Beirut's southern suburbs and in southern Lebanon along the disputed border with Israel, according to the state-run National News Agency.

Both are strongholds of the Iran-backed Hezbollah militant group, whose leader, Hassan Nasrallah, had close ties to Soleimani. A picture of Nasrallah hang in Soleimani's home.

Palestinian factions in the Gaza Strip, including the territory's Hamas rulers, opened a mourning site for the slain general and dozens gathered to burn American and Israeli flags.

The killing of Soleimani was "a loss for Palestine and the resistance," said senior Hamas official Ismail Radwan.

El Deeb reported from Beirut. Associated Press writers Joseph Krauss in Jerusalem, Jon Gambrell and Aya Batrawy in Dubai, United Arab Emirates; Amir Vahdat in Tehran, Iran; Zeina Karam in Beirut and Fares Akram in Gaza City, Gaza Strip contributed.