U.S. Secretary of Defence Donald Rumsfeld said Friday the newly-launched air campaign against Iraq is historically unparalleled in terms of accuracy and efficiency.

"What is taking place today is as targeted an air campaign as has ever existed," Rumsfeld told reporters at a Pentagon briefing.

But critics accused Rumsfeld of attempting to win a public relations war in the face of opposition to the U.S.-led war.

U.S. bombs and missiles struck Baghdad in two separate attacks Friday night, with presidential palaces and command and control centres targeted each time.

Rumsfeld said he felt compelled to speak about the precision of the so-called "Shock and Awe" campaign after he overheard reporters in Washington comparing it to bombing campaigns during the Second World War.

"There is no comparison," he said. "The weapons that are being used today have a degree of precision that no one ever dreamt of in a prior conflict. It's not a handful of weapons, it's the overwhelming majority of the weapons."

The U.S. claims that 90 per cent of its bombs and missiles are of the precise, smart bomb variety.

Rumsfeld said the nature of the bombing is intended to attack only military targets while minimizing civilian casualties.

"The targeting capabilities and the care that goes into the targeting to see that other targets are not struck is as impressive as anything anyone could see," said Rumsfeld.

"The comparison (to the Second World War) is unfortunate and inaccurate. Those were dumb bombs, and they were spread across large areas. These are very precise weapons."

"Every single target has been analyzed and the weapon has been carefully selected," said Rumsfeld. "The direction in which the weapon is delivered has been carefully examined and the time of the day when there is the greatest prospect of minimizing any innocent lives. It is an enormously impressive effort, a humane effort."

In an interview with CTV, former Congressional adviser Michael O'Hurley-Pitts said he was "skeptical" about the number of smart bombs.

"I continue to be skeptical that 90 per cent of the ordnance being used is smart bombs. The potential for civilian casualties remains high."

O'Hurley-Pitts said the problem was compounded by the fact that the Iraqi military infrastructure is integrated into central Baghdad, a densely populated area. He said global opposition to the war, particularly in Arab nations, meant the U.S. was working hard to keep public opinion on its side.

"The U.S. is greatly concerned what Middle Eastern people are seeing," he said. "Needless death of civilians will cause a lot of outrage in the region."

Maj. Gen. (Retired) Lewis MacKenzie said he agreed, and that he was "confused and bemused" by the bombing, given the relative ease with which allied forces are advancing across the desert towards Baghdad.

Rumsfeld also said the current conflict was "historic" because information was so readily accessible to media outlets and journalists the world over.

"I doubt that in a conflict of this type there has ever been the degree of free press coverage as you are witnessing in this instance," he said.