"It's an indication of the kind of excitement and anticipation that has been present here for at least four hours in the heat at Karachi international airport."
More than 20,000 police and troops, backed up by bomb squads, patrolled the route of Bhutto's planned homecoming parade from the airport to the mausoleum of Muhammad Ali Jinnah, Pakistan's founding father.
Burly security guards with portraits of Bhutto on their T-shirts also lined the streets.
"I love Benazir and we are here to safeguard her life. I can sacrifice my life for her," said Abdul Majid Mirani, a guard in a 5,000-strong private army tasked with protecting her.
Karachi was decked out with massive billboards of Bhutto and her father, Zulfiqar Ali Bhutto, who was executed in 1979 by the military government that ran the country.
Commenting to Al Jazeera on the crowds gathering in Karachi, Ikram Sehgal, a political analyst, said: "Obviously she has a mass following and that following makes her a major factor in Pakistani politics, but the welcome that is being seen here is not unprecedented - if it wasn't like this, it would be a surprise."
But in Islamabad, Pakistan's capital, the mood was far quieter. Kamal Hyder, Al Jazeera's correspondent in Islamabad, reported: "It's business as usual here."
"Her [Bhutto's] return may be a big event for her supporters, but across the country there will be a lot of people questioning where the country will go from here," he said.
"Pakistan needs a military leader who can control both civil and possible military extremism"
Creative_person01, Islamabad, Pakistan
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For years, Bhutto has said she will return to Pakistan to put an end to the military's position in power.
Before boarding her flight from Dubai to Karachi, Bhutto told reporters: "Pakistan is standing at a very critical juncture. One route leads to democracy, and the other leads to dictatorship."
But now she is returning as a potential ally for General Pervez Musharraf, Pakistan's president and the army chief who seized control in 1999, in an upcoming general election.
The US is believed to have encouraged their alliance in order to keep Pakistan, its ally, committed to fighting al-Qaeda and supportive of Nato's work in Afghanistan.
The former leader's imminent return appeared to please investors, with the Karachi Stock Exchange (KSE) benchmark 100-share index up around one per cent, amid the hope that her return bodes well for stability and democracy.
But the Pakistani authorities say that Bhutto could be a target for al-Qaeda fighters when she returns.
"She has an agreement with America. We will carry out attacks on Benazir Bhutto as we did on General Pervez Musharraf," the Reuters news agency reported Haji Omar, a Taliban commander in Pakistan's Waziristan tribal region, as saying.
Bhutto's procession through Karachi could take up to 18 hours and she will be protected by bullet-proof screens as she rides in a specially modified vehicle.