On Sept. 21, al-Shabaab insurgents stormed Nairobi’s Westgate mall, killing at least 72 and leaving 175 injured.

Affiliated with al-Qaeda as of last year, al-Shabaab claims that the attack was in response to a prolonged Kenyan military presence in Somalia. Kenya first intervened militarily in 2011, when al-Shabaab cut off humanitarian aid into southern Somalia.

After the initial Westgate siege, terrorists held and tortured hostages inside the mall for nearly 72 hours. Besides hostages, other victims stranded in the mall struggled to avoid detection by terrorists.

“I was next to this teenage boy who was laying flat on his tummy,” Sneha Mashru, a radio presenter who was trapped in the mall told Euronews. “I realized he was shot because he was bleeding … so I took a lot of his blood, as much as I could, and I tried to put it on myself to pretend that I was dead.”

Charlotte, N.C., native Katherine Walton found herself in a toy store with her three young daughters. Her two older children were in a different store at the time of the attack.

“My two-year-old immediately crawled up in a fetal position facing the floor and just stayed in a ball,” Walton said. “She was so still that I kept touching her to check that she was still breathing.”

Walton and her children were rescued by Abdul Haji, a civilian who provided cover fire and rescued roughly 1,000 people from the mall.

Amidst the four-day hostage crisis, Kenyan President Uhuru Kenyatta repeatedly reassured Kenyans that his troops were regaining control of Westgate. Members of al-Shabaab were quick to retaliate using Twitter to announce that they were “still inside the mall fighting the (Kenyans).”

Finally, on Sept. 24, Kenyatta announced that all of the attackers had been “ashamed and defeated.”  Five terrorists from al-Shabaab were killed in the mall, and the remaining were captured alive.

Recent evidence, including blueprints of Westgate and concealed weapons inside the mall, suggests that the siege had been meticulously calculated.

Equally well planned, one could argue, is al-Shabaab’s recruitment strategy.  Two of the terrorists have been confirmed to be of American origin.

Jeremy Rinker, visiting assistant professor of peace and conflict studies, suggests the source of the problem is a lack of needs being met for these young men in high conflict areas.

“It’s easy to prey on that frustration, and groups like al-Shabaab have become very adept at handling that,” Rinker said.

Although there is no evidence linking her to the attack, authorities fear that Samantha Lewthwaite, dubbed the White Widow, was involved in plotting the attack.

After her husband died as a suicide bomber in the London attacks in 2005, Lewthwaite fled to Kenya, where she is currently wanted on charges of a 2011 conspiracy to attack Kenyan hotels and restaurants. Allegations of a recent connection to the Westgate shooting have heightened the search for the elusive White Widow.

Since the attack, many in Kenya have declared a need to revamp security. They argue that a Kenya-Somalia border susceptible to illegal immigration accounted for Somali insurgents entering the country unnoticed.

“Kenya needs to bring its citizens together to recognize security threats, to mobilize them into a common security consciousness and surveillance system that they trust and have confidence in,” Godwin Murunga, deputy director of the African Leadership Centre in Nairobi wrote in an article for CNN.

While it remains unclear whether Kenyatta will tighten border control, it is clear that his troops will remain in Somalia.

“We went as a nation to Somalia to fight the war against terror unleashed on Kenyan people, Somali people and people around the world,” Kenyatta said this week. “This is not a Kenyan war, this is an international war.”