The Country Reports on Terrorism by the US State Department, released on 19 June, reveals Isis has beaten al-Qaeda as the world's leading terrorist organisation.
The new report found that the Islamic State in the Middle East, as well as its partner Boko Haram in Africa, has led to the decline of al-Qaeda's power. It reported that al-Qaeda leadership "appeared to lose momentum as the self-styled leader of a global movement in the face of Isil's [Isis] rapid expansion."
However, the report noted that al-Qaeda continued to have an impact on terrorism.
"Though AQ central leadership was weakened, the organisation continued to serve as a focal point of 'inspiration' for a worldwide network of affiliated groups, including al-Qa'ida in the Arabian Peninsula—a long-standing threat to Yemen, the region, and the United States; al-Qa'ida in the Islamic Maghreb; a;-Nusrah Front; and al-Shabaab," the report said.
The report also found that nearly 33,000 people were killed and another 34,700 were injured in about 13,500 terrorist attacks around the world last year. According to NBC News, that equates to a 35% increase in terrorist attacks and an 81% rise in fatalities since 2013.
CNN reported that 24 Americans died last year in terrorist attacks, specifically in Afghanistan, Jerusalem and Somalia.
The attacks, which were dominate in Iraq, Pakistan, Afghanistan, India, Nigeria and Syria, happened in 95 countries total.
More aggressive and ruthless attacks
Terrorist groups were conducting more aggressive attacks, which included "ruthless methods of violence such as beheadings and crucifixions intended to terrify opponents". Isis and Boko Haram also employed tactics such as "stoning, indiscriminate mass casualty attacks, and kidnapping children for enslavement".
Isis is credited with the largest number of attacks last year, but it came in second to Boko Haram in the number of fatalities, CNN reported.
The report noted that Isis has a powerful social media presence that allows it to spread its message and recruit fighters. Isis "has been adroit at using the most popular social and new media platforms (YouTube, Facebook and Twitter) to disseminate its messages broadly," the report said.
According to the State Department, the Syrian civil war is a "significant factor" in the rise of terrorist attacks last year. Failed and weak governments were also blamed for enabling the growth of terrorist groups.