At least 14 people have been killed and more than 80 injured in a series of apparently coordinated car bomb attacks in Baghdad Thursday.

It is the latest attack in what has become one of the worst periods of violence in the country since the departure of US troops 18 months ago.

The New York Times reported that one bomb exploded just 200-300 meters outside Baghdad’s international zone, close to Iraq’s Foreign Ministry, killing four people and wounding 12.

Other bombs targeted districts populated by the country’s Shi’a Muslim majority, including one bomb in the al-Shurta al-Rabaa district, which was planted on the trailer of a tractor laden with gas cylinders, also killing four people and injured scores more.

Iraqi government and western officials are concerned that a resurgent Al Qaeda in the Middle East is posing an increasing threat to the stability of the entire region. The Iraqi branch of Al Qaeda – which had previously suffered severe setbacks in its campaign – has emerged stronger than ever after merging with Syrian jihadis to become the Islamic State of Iraq and al-Shams (ISIS). That group recently claimed responsibility for a massive jailbreak in which hundreds of senior, veteran Al Qaeda fighters were freed from Iraqi prisons, where many had been held on death row for their part in deadly terror attacks.

The US government has recently stepped up its campaign of drone strikes against what it still considers as one of the most dangerous Al Qaeda branches, the Yemen-based Al Qaeda in the Arabian Peninsula (AQAP).

That escalated campaign came after the US ordered the emergency closure of 22 U.S. diplomatic facilities in 17 different countries last week, as the result of a specific threat from AQAP, as well as other Al Qaeda affiliates in the Middle East and North Africa.

Recently, Foreign Policy reported on claims by terrorism experts that the Islamist terrorist group is in the process of shifting its “center of gravity” from Pakistan – where Al Qaeda’s central leadership has been based since its ejection from Afghanistan in 2002 – to Yemen, in the Middle East.

According to the experts cited in the report, Al Qaeda no longer relies on a single “charismatic” leader like Osama Bin Laden, and posses “the ideological ammunition, ideological fuel which is helping them stay afloat” independently of the Pakistan-based branch led by Bin Laden’s former deputy Ayman Al-Zawahiri.

Yemen would be a more strategically-placed based for Al Qaeda operations than Pakistan, since the organization’s main theaters of battle have shifted from Pakistan and Afghanistan to the Middle East and Africa, with ongoing conflicts in Yemen, neighboring Somalia, Iraq, Syria and the Sinai Peninsula, among other places.