IMPEACH BUSH

BAGHDAD - A sharp increase in mortar attacks on the Green Zone — the one-time oasis of security in Iraq's turbulent capital — has prompted the U.S. Embassy to issue a strict new order telling all employees to wear flak vests and helmets while in unprotected buildings or whenever they are outside.

The order, obtained by The Associated Press, has created a siege mentality among U.S. staff inside the Green Zone following a recent suicide attack on parliament. It has also led to new fears about long-term safety in the place where the U.S. government is building a massive and expensive new embassy.

The situation marks a sharp turnaround for the heavily guarded Green Zone — long viewed as the safest corner of Baghdad with its shops, restaurants, American fast-food outlets and key Iraqi and American government offices.

The security deterioration also holds dire implications for the Iraqi government, which uses the Green Zone as a haven for key meetings crucial to its ability to govern. On Wednesday, for example, Vice President Dick Cheney held meetings in the Green Zone with Iraq's prime minister.

Reporters covering the Cheney visit were hustled into a secure area when a large explosion rattled windows in the U.S. Embassy late in the afternoon. Cheney spokeswoman Lea Anne McBride said the vice president's meeting "was not disturbed and he was not moved."

The increase in mortar attacks comes despite the presence of tens of thousands more American and Iraqi soldiers in the streets of Baghdad as part of the security crackdown ordered by President Bush in January.

The vest and helmet security order was issued May 3, one day after four Asian contract workers working for the U.S. government were killed when rockets or mortars slammed into the Green Zone.

It was at least the third straight day of barrages against the 3.5-square-mile area along the west bank of the Tigris River in the center of Baghdad.

Because of the "recent increase of indirect fire attacks" — the military term for mortar and artillery barrages — the order told embassy employees that until further notice, "outdoor movement" must be "restricted to a minimum."

"Remain within a hardened structure to the maximum extent possible and strictly avoid congregating outdoors," the order said.

Government employees who work outside of a "hardened structure" such as the current embassy building or travel "a substantial distance outdoors" must wear "personal protective equipment," meaning flak jackets and helmets, the order said.

A U.S. Embassy spokesman confirmed the order was in effect until further notice. But he refused to say more, citing security, and would not allow his name to be published, citing embassy regulations.

Attacks on the Green Zone are nothing new: They have occurred from time to time since the first months of the U.S. presence in Iraq. Often, the rounds landed in open fields — part of a system of parks that Saddam Hussein built when the area served as the headquarters of his regime.

But the latest attacks have been unnerving because of their frequency, the size of the ordnance and the accuracy of some hits.

Some rounds appear to have been fired from Sunni insurgent strongholds to the south of the Green Zone. Others have come from areas where Shiite militiamen operate.

At last week's regional summit in the Egyptian resort of Sharm el-Sheik, U.S. Ambassador Ryan Crocker said it was unclear if the attackers were becoming more skilled, had better weapons or tools or were just getting lucky.

He noted that it was difficult to stop mortar attacks. Extremists can carry the weapons in vehicles, set up quickly, fire them and drive away.

It is also likely that rounds fired from Shiite areas are intended as a warning to Iraq's Shiite-led government not to bow to American pressure and disband the militias.

One rocket exploded near Prime Minister Nouri al-Maliki's office in March during a press conference for visiting U.N. Secretary-General Ban Ki-moon, who ducked behind the podium as the blast showered small bits of debris from the ceiling. Two Americans — a soldier and a contractor — died in that barrage.

A few days later, two suicide vests were found unexploded in the Green Zone, presumably smuggled in by someone with a security pass to enter the fortified area.

And on April 12, a suicide bomber managed to penetrate the Green Zone's numerous security checkpoints, detonating an explosive belt in the cafeteria of the Iraqi parliament building. One Iraqi lawmaker was killed. A U.S. Embassy employee was inside the building when the bomb went off, but far enough away to escape injury, according to two other American employees who spoke on condition of anonymity for fear of violating regulations.

All that has raised the anxiety level among American staffers, who must contend with long working hours, broiling summer heat and separation from families. In the past, they could take comfort from the fact that they were assigned to the safest corner of Baghdad rather than to military bases hammered routinely with rockets and mortars.

But security has now become a prime topic of discussion among embassy staff. Many are increasingly worried and even glum — although few want to complain publicly, said the two American employees who spoke anonymously.

They are especially worried about their sleeping quarters in trailers on the current embassy compound — fearing that mortars could crash through the thin roofs as they sleep, the two said.

The embassy does not release security details such as how many people sleep in the trailers or who sleeps in more secure areas. It says such details are confidential information that could put lives at risk if released. But most employees now sleep in some type of temporary housing, such as the trailers.

Many employees also worry about the future — fearing that the new embassy, when it opens, will not contain enough rooms for all American staff and some might have to remain in the trailers at risk of mortars, the two employees said.

The issue has become part of the debate in the U.S. Congress over Iraq funding. Democrats in Congress have pushed for a reduction of Baghdad embassy staffing overall, and for housing facilities within the new embassy compound when it opens, but the issue remains undecided.

Associated Press reporters Anne Gearan and Matthew Lee contributed to this report from Washington.