Prime Minister Nouri al-Maliki is having a tough time trying to dislodge al-Qaida forces who hold much of the western cities of Fallujah and Ramadi because his army doesn't seem to be up to the task, despite emergency shipments of U.S. arms.

At the same time, Sunni tribal leaders are shunning the Shiite premier's appeals to help him battle this new insurgency.

The Sunnis' reaction to the jihadist offensive is not surprising since it was a brutal government crackdown on protests by the minority sect, incensed at being oppressed and marginalized by Maliki's Shiite-dominated regime, that al-Qaida exploited when it seized the cities in western Anbar province Dec. 30.

In recent days, the jihadists have escalated attacks in Baghdad and other important cities like Kirkuk and Mosul in the north to pin down large military forces there and prevent their deployment to embattled Anbar province.

"The security situation will continue to be tense, bloody and with escalating attacks for the immediate short-term as Maliki weighs the political versus security costs of launching large-scale military operations against the insurgent targets ahead of this year's parliamentary elections," the U.S. global security consultancy Stratfor said.

Al-Qaida in Iraq's seizure of Fallujah and Ramadi was seen as part of a plan to establish a jihadist emirate in western Iraq -- an overwhelmingly Sunni region that borders war-torn northern Syria -- where the Islamic State of Iraq and the Levant, an AQI offshoot, is battling to set up a similar emirate.

The jihadist forces in Syria are battling other rebel groups, some Islamist but mostly secular nationalist organizations, as well as the Damascus regime. So their efforts have been less successful than AQI's offensive in Anbar.

But their ultimate objective is to establish a jihadist state in the heart of the Arab world, from which to mount offensives in Lebanon, Turkey, Jordan and the West Bank.

Recent attempts by the jihadists, who seek to restore an Islamic caliphate that 1,300 years ago stretched from Spain to Indonesia, to seize and hold large territories have failed in Afghanistan, Algeria, Mali and Yemen.

The jihadist takeover of Fallujah, 50 miles west of Baghdad, and nearby Ramadi, marked the first time since the height of the insurgency that followed the 2003 U.S. invasion of Iraq that militants have taken control of major cities.

Maliki's forces have made some progress in driving the jihadists out of some parts of Ramadi, the provincial capital. But al-Qaida remains well entrenched and controls most of Fallujah, a city of 300,000 that was twice a major battleground for U.S. forces in 2004 and 2008.

Some tribal leaders and officials report in recent days the jihadists have even been reinforced by some 400 fighters and heavy weapons, including 23mm Soviet-era anti-aircraft guns that are deadly when used as infantry weapons in urban fighting, and Grad battlefield rockets.

These forces are infiltrating into Fallujah through its southern districts which are reportedly held by Sunni tribes opposed to Maliki's regime and currently allied with al-Qaida in Iraq.

Maliki had planned to mount an all-out offensive on Fallujah to drive out the jihadists 10 days ago, but postponed it claiming he wanted to spare the inhabitants of the city.

But that underlined his lack of trust in his Shiite-dominated army and security services since U.S. forces completed their withdrawal in December 2011.

Washington refuses to send troops back into Iraq to support Maliki, but is airlifting arms and ammunition, and is reportedly setting up training for Iraqi forces in neighboring Jordan.

Deputy Interior Minister Adnan al-Asadi Sunday charged the jihadists have moved "huge and advanced" weapons systems in Fallujah that he said are "enough to occupy Baghdad."

A jihadist assault on the heavily guarded capital seems far beyond AQI's capabilities even with thousands of tribal allies incensed at Maliki's increasingly autocratic regime.

But Interior Ministry spokesman Saad Maan Ibrahim has said if Maliki had not moved against the jihadists "there would have been an assault on Baghdad."

Observers suspect Maliki's regime is playing up the jihadist threat in hopes of convincing the Americans, dismayed at the rising surge of jihadist violence over the last year, to provide greater military support to counter the Islamists' strongest challenge to his rule since the U.S. pullout.