By Jim Muir
BBC News, Baghdad
Cultural barriers mean police have difficulty searching women
Monday's triple suicide attack against Shia pilgrims in Baghdad highlighted what seems to be a growing phenomenon - the use by Sunni-based radical Islamist insurgents of women to carry out suicide attacks.
Police said all three of the attackers in the bombings, which claimed the lives of about 25 pilgrims, were women.
Eyewitnesses in the city of Kirkuk - where at least 22 people were reported to have been killed by a suicide bomb attack on a crowd of protesting Kurds - said the attacker there was also a woman.
American military figures indicate that there have been at least 27 suicide bombings carried out by women in Iraq this year, a sharp jump from only eight in 2007.
The increase is even more significant given the fact that the number of attacks of all kinds has dropped sharply over the past year.
The greater use of individual suicide bombers on foot seems to reflect the fact that it has become more and more difficult for insurgents to assemble bigger bombs.
These bombs have in the past been packed into cars and vans driven by suicide attackers or detonated at the roadside.
Such attacks are still happening, but far less frequently than a year or two ago.
The Khadimiya pilgrimage - one of the three biggest events in the Iraqi Shia calendar - was a case in point.
Security in Khadimiya itself, where the pilgrimage reached its climax on Tuesday, was so stringent that smuggling a big bomb into the area would have been extremely difficult.
The area of the Khadimiya shrine had been put under tight security
So the bombers were reduced to blowing themselves up among the throngs of pilgrims straggling along many miles of roads leading to the site - a target so soft that it was virtually impossible to protect completely.
The use of women makes it doubly difficult for the security forces.
"We can't search everybody on the streets," said a police source after the latest explosions.
"And with women it's even more difficult, since they can hide the bombs under their robes, and policemen can't body-search them."
"The terrorists are attacking the easiest targets - crowded streets, markets and so on - just to deliver the message: We're still here."
"The only thing we can do is to keep up the pressure on the insurgents and keep them off-balance."
Measures were taken to stop the bombers reaching anywhere near the Khadimiya shrine itself and about 200 policewomen were drafted in to conduct body searches of all female pilgrims trying to enter the area.
But once a woman suicide bomber is loose on the street, and looking for a soft target, the only question is how many people she will manage to take with her or leave maimed.
So some effort is now being made to dissuade potential women bombers from taking that path.
In Diyala province, the focus of a new security campaign that began on Tuesday, there have been several female suicide bombings in recent months.
It is rumoured that the bombers who attacked the Khadimiya pilgrimage also came in from Diyala province, which is just to the north-east of Baghdad.
Last week, a group of 150 female police graduates in Diyala were recruited to a special unit, called "Banat al-Iraq" or Daughters of Iraq.
Their task is to approach women thought to be vulnerable to Islamist manipulation, and persuade them that suicide operations are wrong.
It is hoped that that, coupled with redoubled efforts to track and interrupt the flow of explosives and the assembly of suicide bombs, could help reduce the number of incidents.
But if the materials and motivation are still there, even a greatly improved security situation will not be able to stop bombers willing to give their own lives to take those of others.