Well, the Islamic State had quite a week.

After more than a year of clashes with Iraqi forces and with opposition groups in Syria, the militant group claimed two major cities, showing both the Iraqi army's weaknesses and the militant group's growing power.

The United States reacted to this by reportedly accelerating the delivery of weapons to Iraq, while organizations like the United Nations have expressed fears that the militants could destroy the ancient ruins in Palmyra, a World Heritage site.

Ramadi

The capital of the Anbar province was a major battlefield in the counterinsurgency that overtook Iraq in 2006-2007. The city's fall to the Islamic State was not only a strategic win for the group, but highlighted the Iraqi military's poor condition and the government's shortcomings.

As the Post's Hugh's Naylor writes, Ramadi's loss was a huge blow to a strategy to build an "effective Sunni fighting force" to counter militants.

The fall of Ramadi amounts to more than the loss of a major city in Iraq’s largest province, analysts say. It could undermine Sunni support for Iraq’s broader effort to drive back the Islamic State, vastly complicating the war effort.

After taking over the city, supporters of the group took to the streets, shot bullets in the air and passed out candy to crowds.

Along with chants of "Allahu Akhbar," others proclaimed, "Baghdad and Karbalah will be next."

Palmyra

The city,  located in the heart of Syria and known for its archeological gems, has been faced with extreme violence as the jihadists descend upon the region. But another troubling factor here is the Islamic State's track record of destroying meaningful historic artifacts and sites, as they have done numerous times before in Iraq.

My colleague Ishaan Tharoor explains the significant historic value these ancient ruins have:

Palmyra, which is located in the center of Syria, was an old oasis town that turned into an influential desert crossroads for around the first century A.D., at a time of significant Roman influence in the Near East. Its architecture and artifacts reflect its place as a meeting point between civilizations and cultures. Some of Palmyra's major structures are considered to be among the best-preserved examples of Roman antiquity.

A 'march to cleanse'

Although Palmyra and Ramadi were major gains for the jihadists, they also seized villages that bordered both cities as well as a town that sits at the Syria-Iraq border, further connecting the two countries the group calls its Caliphate.

In a message translated by the the SITE Intelligence Group, the Islamic State claims that it seeks to not just control these regions, but to "cleanse" them.

Read related content::