A portion of the new U.S. embassy under construction is seen from across the Tigris river May 19, 2007, in Baghdad. U.S. diplomats will begin moving into the mammoth new heavily fortified embassy next month after long delays in the 36 million project.

Washington ? U.S. diplomats will begin moving into the mammoth new, heavily fortified embassy in Baghdad next month after long delays in the $736 million project – and not a moment too soon. Increasing rocket attacks on the Green Zone have killed four Americans in recent weeks and have embassy staff wearing body armor and ducking for cover.

U.S. Ambassador to Iraq Ryan Crocker said Friday that construction is complete at the Vatican-sized compound and that although not all buildings have yet been certified for final occupancy, transition to the facility from the less-protected location in a Saddam Hussein-era palace should start at the end of May.

“It’s been a difficult few weeks, rockets are bouncing off your buildings, and maintaining focus can be an occasional challenge,” Crocker said, referring to the recent spate of insurgent attacks in the Green Zone that have killed at least two U.S. soldiers and two American civilians.

“We will begin moving into the new embassy – some of the office space and the apartments – probably the end of next month, the beginning of June, so that will certainly improve quality of life and provide some added protection,” he told reporters.

The rise in insurgent attacks prompted the embassy late last month to order personnel not to leave reinforced buildings and to wear helmets and body armor if they must go outside. A shortage of space in fortified areas has forced some diplomats to sleep at the new embassy site despite the lack of occupancy approvals.

“We worry a lot less about formal safety certifications and a lot more about ensuring people have a place to sleep where rockets couldn’t get at them,” said Crocker, who has served in battle zones before, notably in Lebanon during its civil war in the 1980s.

“Being under attack is a lot like being under attack, whether it is in Lebanon or Iraq,” he said. “The incoming sounds about the same and has about the same impact.”

The new embassy will be the largest U.S. diplomatic mission in the world, with fortified working space for 1,000 people and living quarters for several hundred on a 104-acre site.

But the project has been beset by construction, logistical and security hitches that caused major delays beyond its planned September 2007 opening date and angered some lawmakers.

In October, the department conceded that a host of problems, including major malfunctions in the complex’s physical plant, including electrical and water distribution systems, would push back the embassy opening at least until this spring. Some of those problems have since recurred.