Al-Qaida and its allies have unleashed a wave of suicide bombings across the Middle East and other regions in which hundreds of people have been killed, suggesting a jihadist resurgence.

Iraq, Yemen, Pakistan, Algeria, Mali, Egypt, Libya and, probably most dangerously, Syria have all been gripped by a surge of jihadist violence and a new chapter of constantly changing Islamic extremism seems to be evolving.

It's not clear if the attacks are coordinated. The original al-Qaida Central, established by Osama bin Laden and Ayman al-Zawahiri, the longtime Egyptian deputy who succeeded him, isn't believed to have controlled the global network for several years.

These days, largely grassroots jihadist groups, such as al-Qaida in the Islamic Maghreb in North Africa and al-Qaida in Iraq, operate independently. The groups are connected by a core of seasoned, hard-line operatives who have spread around the world and some see the hand of Zawahiri, long the eminence grise behind bin Laden.

In recent weeks, the surge in suicide bombings, the signature tactic of these so-called holy warriors, suggests that they no longer seem to be in terminal decline after several years of an aggressive U.S.-led campaign to decapitate and dismantle the organizations.

They appear to making significant headway, as witness the jihadist seizure of northern Mali, an area the size of France, in 2012.

Among the recent suicide attacks:

-- at least 33 people were killed Sunday in Kirkuk in northern Iraq when a suicide bomber detonated a truckload of explosives outside a police headquarters, apparently seeking to inflame sectarian conflict between rival Sunnis, Shiites and Kurds.

AQI, once weakened by U.S. forces that withdrew in December 2011, has been given immense impetus by the inflow of arms and seasoned fighters from neighboring Syria.

-- The al Nusrah Front, the leading jihadist force in Syria, claimed responsibility for Jan. 21 and 23 suicide attacks on Syrian military bases, in which two trucks, one reportedly loaded with 20 tons of explosives, the other with 3.5 tons, were employed.

Al Nusrah Front, led by Iraqi veterans who fought the Americans, has claimed 48 of 58 suicide attacks in Syrian since December 2011.

-- On Jan. 16, an AQIM force of some 30 jihadists from Libya seized the In Amenas natural gas complex in southeastern Algeria. Special Forces killed most of the attackers, and 38 foreign hostages also perished, in a four-day siege.

U.S. officials say the operation was planned as a massive suicide mission in which the whole facility was to be blown sky-high.

All this is taking place 20 months after U.S. Special Forces assassinated bin Laden, al-Qaida's iconic founder and leader, in his Pakistani hideaway, a milestone in the battle against jihad.

"When Osama bin Laden was killed ... a long, bloody and controversial battle seemed to be drawing to a close," Roula Khalaf and James Blitz observed in the Financial Times.

"Yet today, the threat from jihadis appears once again to be on the rise, though it has taken a more nebulous, multifarious face."

But, possibly more worryingly, al-Qaida's resurgence is happening in the political turmoil triggered by the so-called Arab Spring in early 2011 in which long-suppressed Muslims rose up to bring down powerful dictators in a wave of pro-democracy uprisings.

They did in eight months what the jihadists has failed for years to achieve. Among the victims was Moammar Gadhafi, longtime leader of Libya killed at the end of an 8-month civil war in October 2011.

It looked for all the world as though the Islamist extremists had been shunted aside by people power. But they've managed to exploit the post-revolution disorder and the ideological void to their advantage, particularly in Syria, a pivotal Arab state allied with Iran.

In Syria, resilient jihadists are the most effective group fighting to bring down the brutal regime of President Bashar Assad, and may emerge as the most dominant force in any successor regime.

"Long before Moammar Gadhafi was ousted in Libya, jihadists and other militants thrive in power vacuums," the U.S. global security consultancy Stratfor noted.

"This assertion has proved true in Afghanistan, Iraq and Somalia, and more recently in Libya, northern Mali and now Syria. Weapons flooding into such regions only compound the problem."