BAGHDAD, Iraq (CNN) -- Iraqi security forces and U.S. troops imposed stiff security across Baghdad on Thursday as hundreds of thousands of Shiite faithful made their annual trek to the shrine of a fabled and beloved imam.
So far, there have been no reports of sectarian or insurgent violence, but there was one accident -- sparks on a Baghdad train carrying pilgrims left one dead and seven injured, according to the Iraqi Interior Ministry.
Marchers beating their chests and dancing in circles in the traditional Shiite fashion trod toward the Kadhimiya shrine to commemorate the death of eighth-century imam Musa al-Kadhim, the seventh of the 12 early imams revered by the Shiites. Watch throngs pack the streets of Baghdad »
TV footage showed the faithful, from other countries as well as Iraq, at the golden-domed shrine. They surrounded the imam's tomb, touched the bars of the tomb and recited prayers.
Two years ago, nearly 1,000 people died when rumors of a suicide bomber in the crowd of pilgrims sparked a stampede. Many of those people fell from a bridge and drowned in the Tigris River.
That bridge has since been closed and marchers from the Shiite eastern side of the city have had to take ferries or cross bridges farther south. Many of the marchers are trekking up Haifa Street, long a perilous stretch, in a straight route to the shrine.
Marchers walked past reinforced Iraqi and U.S. security checkpoints. Some chanted "leave, leave Iraq" as they strolled by American soldiers on Thursday.
But religious sentiment was the theme of the day. The faithful sang religious songs and carried green Islamic flags. There weren't seas of marchers holding up pictures of their favorite political leaders, as in past pilgrimages.
In the past, violence has erupted during the event, a reality that led to a three-day government-imposed vehicle ban that is to end Saturday at dawn. That ban has greatly inconvenienced many residents and has led businesses to close during the ban, leaving many workers temporarily without work and paychecks.
"I have come here to get the blessing of the martyr imam and to challenge the terrorism of the Wahhabists," said Hussein Mizaal, 21, a student from southeastern Baghdad, the Associated Press reported. "We are not afraid of anyone except God. Our faith is getting stronger despite their mean attacks," he said, referring to the Wahhabi sect of Sunni Islam practiced in Saudi Arabia.
There have been other disasters at the event in the recent past linked to the Sunni-Shia sectarian divide. Pilgrims, for example, have been given poisoned food. This year, a committee of Shiite groups is offering food to the pilgrims.
Iraqi Prime Minister Nuri al-Maliki was on a journey of his own, meeting with Iranian leaders in Tehran.
Iran's President Mahmoud Ahmadinejad told al-Maliki that stability in Iraq is all-important for the future of the region, the Iranian-run Islamic Republic News Agency reported Thursday.
"Iran and Iraq have a heavy responsibility for establishing peace and security in the region," Ahmadinejad said, according to IRNA.
"Terrorists want to dominate our potentials in political, economic and culture fields, but by grace of God we will neutralize their plots," al-Maliki said, according to IRNA.
"Today, Iran, Iraq and all countries of the region must fight against terrorism."
The United States has asserted that Shiite militants in Iraq are being armed and trained by Iranian agents, but Iran has denied that claim.
President Bush on Thursday said Iranians who smuggle bombs to insurgents in Iraq will face "consequences" if they continue.
Speaking at a press conference, Bush said one of the main reasons he asked U.S. Ambassador to Iraq Ryan Crocker to meet with Iranians in Iraq "was to send the message there will be consequences" for those who transport explosively formed penetrators into Iraq.
"He [al-Maliki] knows that weaponry being smuggled into Iraq from Iran and placed into the hands of extremists -- over which the government has no control, all aimed at killing innocent life -- is a destabilizing factor," Bush said.
CNN's Mohammed Tawfeeq in Baghdad and Joe Sterling in Atlanta contributed to this report.