Angelina Jolie, who is rumoured to be pregnant with twins, donned a helmet and flak jacket as she visited Iraq as part of her role as a UN goodwill ambassador.

The 32-year-old accompanied the U.S State Department on the trip to learn about the plight of 4 million displaced Iraqis.

Her partner Brad Pitt remains on dad duty in LA, where he was spotted yesterday with the couple's adopted daughter Zahara in tow.

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Ready for battle: Angelina dons helmet and flak jacket in Iraq yesterday

Angelina shares a meal with troops stationed in Iraq

Of her mission, Angelina has said: "There's lots of goodwill and lots of discussion, but there seems to be just a lot of talk at the moment, and a lot of pieces that need to be put together.

"I'm trying to figure out what they are.”

"What happens in Iraq and how Iraq settles in the years to come is going to affect the entire Middle East.

"It's in our best interest to address a humanitarian crisis on this scale because displacement can lead to a lot of instability and aggression."

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Angelina listens to a US State Department official about the work in Iraq

During her trip Jolie dined with U.S troops stationed within the Green Zone, met General David Petraeus, the top U.S commander in the country, Iraqi Prime Minister Nouri al-Maliki and Iraqi migration officials.

The visit comes amid reports Angelina and Brad have increased security at their LA home after daughter Shiloh was targeted by kidnappers, it was claimed today.

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Lunch break: Angelina, who is rumoured to be pregnant with twins, is on the mission as part of her role as a UN goodwill ambassador

According to a US report, a chilling note was left at the door of one of the superstar couple's houses.

It included a photo of the 20-month-old tot - alongside the warning: "We got this close already." An insider said: "They're freaked out.

Angelina spoke to CNN about her work in Iraq

The insider added: "Someone got to their doorstep and left a threat against Shiloh.

"The person included a photo of her, and a note that read, 'We got this close already.'"

The note was left in early January, a US celebrity magazine claimed.

The insider was unable to reveal which house belonging to Pitt, 44, and Jolie, 32, was targeted, because of security reasons.

Shiloh - the couple's only biological child - has not been photographed in public since January 4, according to Life & Style magazine.

Last November, two shots were reportedly fired outside their Los Feliz, California home.

The insider added: "Brad and Angie will do whatever it takes to protect the children.

"There have been frequent threats against their kids, but this time someone just got too close.

"They are by far the most security-conscious celebrities in the world."

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Dad duty: Brad Pitt with adopted daughter Zahara in Los Angeles yesterday

The couple already has impressive security at their California home, which includes a £120,000 state-of-the art control room manned by at least four staff.

Motion tracking cameras with ultra-sensitive detectors alert security to any possible intruders.

Observers say their security bill for 2008 could top £2.5million.

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Scare: Brad Pitt and Angelina Jolie feared daughter Shiloh, bottom right, would be taken

As well as Shiloh, they have three other children, Maddox, six, Pax, four, and Zahara, three.

On 2 February, at the Santa Barbara Film Festival, she said: "I like being a mum. That's my big passion."

A spokeswoman for the couple did not return calls today, but Brad Pitt has reportedly denied Shiloh has been targeted.