The US military surge in Iraq moved into a higher gear yesterday as 10,000 American troops launched a new offensive against Sunni insurgents and al-Qaida jihadis in Diyala province, north-east of Baghdad.
At least 22 insurgents were reportedly killed in initial clashes as US forces moved into western suburbs of Baquba, the provincial capital. US commanders said they believed up to 500 al-Qaida fighters were holed up there.
Even as US forces advanced, terrorists behind the lines exploded a devastating truck bomb at a Shia mosque in the centre of Baghdad. Early reports said at least 75 people were killed and 204 wounded.
The mosque's imam, Sheikh Saleh al-Haidari, said civilian worshippers had been targeted in the blast as they left afternoon prayers. He blamed the attack on "sick souls".
In all, 2,000 insurgents are said to have moved to Diyala from Mosul, Anbar and Baghdad in recent months as US forces tightened their grip in those areas.
The huge ground offensive, which also encompassed parts of western Anbar province and was mounted before dawn with Bradley fighting vehicles and air support, coincided with intensifying US-led operations in southern Iraq.
The primary coalition target in the south appeared to be Shia militia strongholds and forces loyal to the radical cleric, Moqtada al-Sadr, a long-time foe who returned from hiding recently to demand an end to western occupation.
Fierce fighting pitting elements of Mr Sadr's Mahdi army against US, British and Iraqi troops was reported in Amara and Majjar al-Kabir, north of Basra, and in Nasiriya, south-east of Baghdad. At least 30 people have died and about 150 have been injured in the past two days.
Officials in Basra said the assault on the Mahdi army, the biggest since the surge began in February, appeared to the beginning of a long-anticipated American operation to reduce Mr Sadr's power and the spreading influence of his Iranian sponsors.
The US military indicated that yesterday's offensive around Baquba, codenamed Operation Arrowhead Ripper, was the beginning of an open-ended engagement against insurgents displaced from Baghad in recent months. "We are going into the areas that have been sanctuaries of al-Qaida and other extremists to take them on and weed them out," a spokesman said.
Major General Abdul-Karim al-Rubaie, commander of Iraqi forces in Diyala, claimed that torture devices, including handcuffs, electric cables and swords, had been found in safe houses vacated by fleeing insurgents.
President George Bush ordered 30,000 additional troops to Iraq last January in what was seen then as a last-gasp effort to secure Baghdad and surrounding areas and give Iraqi government institutions a chance to function.
Democrats and other opponents of the war in Washington say time is running out, with the Senate leader, Harry Reid, declaring recently that the war was already lost. A Pentagon report last week concluded the surge had failed so far to reduce overall levels of violence.
The twin offensive mounted in the north and south appears to be Mr Bush's answer, and that of his senior commander, General David Petraeus, to the critics at home.
Mr Bush is also redoubling political and diplomatic efforts to turn around the situation in Iraq before what many see as a September deadline for a decision on whether to continue the surge or begin a phased withdrawal.
In recent days the White House has sent a stream of senior envoys to Baghdad, including defence secretary Robert Gates, all demanding faster progress on political reforms.
Mr Bush spent almost an hour on Monday in a teleconference with Iraq's prime minister, Nuri al-Maliki, and other Iraqi leaders. His spokesman said the president was "reassured' by what he heard - but declined to say why.
The strains that Iraq is imposing on the home front were evident again yesterday as news broke of an embarrassing dispute between the state department and Ryan Crocker, the US ambassador to Baghdad, over the quality of US staff assigned to Iraq.
"We cannot do the nation's most important work if we do not have the department's best people," Mr Crocker complained in a memo obtained by the Washington Post.