Every few weeks, right when one extremist group is dominating the news with threats of attacks, along resurfaces another with a different, more harrowing claim.

Over the weekend, Al- Shabaab released a video urging its sympathizers to attack malls in the United States, UK and Canada. The same day, ISIS had one showing its members parading caged captives down the streets of Iraq, the latest in its string of atrocious videos.

Then there's the ever-present threat of al Qaeda, the brutality of the Boko Haram and the looming Taliban.

The United States has a list of 59 designated terror groups, but here are the five that have been making news this month.

Al-Shabaab

What does it want?: It started off with a goal of turning Somalia into a fundamentalist Islamic state governed under Sharia law. It has since expanded into attacks not just at home, but in neighboring Kenya and Uganda.

What's being done?: African Union forces comprising Kenyan, Somali and Ugandan troops are battling the militants in their home country. While the forces have pushed them out of the capital of Mogadishu, the terror group still controls some parts of Somalia and continues its bloody campaign of terror in Kenya and Uganda.

Is it a global threat?: While its attacks have mostly been limited to East Africa, it is getting more ambitious. On Saturday, it posted a video calling on its sympathizers in the West to mimic its attack of a mall in Kenya, a siege that lasted four days and left more than 60 people dead. Homeland Security Secretary Jeh Johnson said there's "no credible or specific evidence" suggesting a U.S. mall attack, but he warned Americans to watch out.

Al Qaeda

What is it?: An extremist group with branches in the Middle East and Africa.

What does it want?: While it has not vocalized its endgame as much, its focus has been targets it considers enemies of Islam or "infidels." It has attacked Western nations, military facilities, even other Muslim sects it considers too liberal. It was behind the September 11, 2001, attacks on the U.S. that killed nearly 3,000 people and struck fear in the hearts of leaders worldwide.

What's being done about it?: Shortly after the attacks, the U.S. teamed up with other nations to launch a war on terror, which led to the death of al Qaeda leader Osama bin Laden. Other nations have been on a campaign to root out any groups with ties to al Qaeda.

Is it a global threat?: Very much so. It has lone-wolf operators worldwide who subscribe to its ideology, but may not have access to a group or command. Most Johnny-come-lately terror groups are also based off of it, and it has carried out suicide attacks in farflung nations such as Indonesia, the U.S., Kenya and Iraq. Its attacks have evolved with security changes, and there's no telling how or where it will strike next. Its growing list of admirers include the Al-Shabaab.

Boko Haram

What is it?: A terror group based in Nigeria.

What does it want?: Its aim is to impose a stricter enforcement of Sharia law across Africa's most populous nation, which is split between a majority Muslim north and a mostly Christian south. In recent years, its attacks have intensified in defiance of the nation's military onslaught. Its ambitions appear to have expanded to the destruction of the Nigerian government. It has been on a campaign of kidnappings and mass killings in the nation's north.

What's being done about it?: Nigerian forces are battling the group with the help of neighboring nations such as Cameroon and Chad. While the U.S. has provided technical and financial support, there has been a reluctance to put boots on the ground unless there's a direct national security threat to the West.

Is it a global threat?: Boko Haram's attacks have been limited to West Africa. But the terror group has targeted western facilities such as the U.N. offices in Nigeria.

ISIS

What is it?: A terror group that operates in Syria and Iraq.

What does it want?: Its ambitions are lofty, its means of achieving them ruthless. It started in 2004 as al Qaeda in Iraq, before rebranding as ISIS two years later. It had similarities with al Qaeda: both were radical anti-Western militant groups devoted to establishing an independent Islamic state in the region. But ISIS has proven to be more brutal and more effective at controlling territory it has seized. It declared a "caliphate" spanning Iraq and Syria and asserted that the group's leader, Abu Bakr al-Baghdadi, is Caliph, the successor to the Prophet Mohammed. It has demanded that all Muslims must offer allegiance to al-Baghdadi.

What's being done about it?: Airstrikes, airstrikes and more airstrikes. Jordan, Egypt and the U.S. are among nations battling the terror group after it released videos showing their citizens' gruesome killings.

Syrian President Bashar al-Assad is also fighting back, though his government's ability to topple ISIS is questionable. Syria's economy has been drained by years of civil war and international isolation. Iraq, on the other hand, is more stable, has more powerful international allies and an effective regional fighting force in the semi-autonomous Kurds.

Is it a global threat?: Yes. Not only does it abduct and behead westerners in the two nations, its popularity is growing and attackers who subscribe to its ideologies have killed people in France and Australia. It's also luring westerners, creating a potential risk for homegrown terrorists.

Taliban

What is it?: A terror group with branches in the Middle East, and that works closely with al Qaeda.

What does it want?: The group ruled Afghanistan until 2001, where it imposed a strict form of Islam law, or sharia. After the 2001 terror attacks, the U.S. invaded Afghanistan and toppled the Taliban. But they remain a violent, conservative force in Afghanistan and neighboring Pakistan. The latter nation's branch goes by Tehrik-i-Taliban Pakistan. Analysts say while it's closely linked with its namesake in Afghanistan as well as with al Qaeda, its primary target is to overthrow the Pakistani state and the military. Its most notable attack was the shooting of Nobel laureate Malala Yousafzai in 2012 as she rode to school in a van.

What's being done about it?: The Pakistani government has tried to hold peace talks with the Taliban, but they have collapsed. Western officials have accused the Pakistani intelligence agency of colluding with militant groups, making distrust a major hurdle to effective collaboration. In Afghanistan, the U.S. and NATO have thousands of troops training Afghan security forces on counterterrorism operations.

Is it a global threat? Yes. It has attacked a series of western facilities, including a U.S. military base in Afghanistan and a consulate in Peshawar.

(CNN)