An American ISIS fighter CNN/screenshot As the global US-led bombing campaign against ISIS approaches its first anniversary, the US is seeing an apparent rise in ISIS-related cases within its own borders.

Since ISIS seized and held its first cities and began building its "caliphate" in January 2015, the group has attracted increasing support from individual Americans who have drawn the attentions of US law enforcement. According to the Center on National Security at Fordham Law, the rate of American individuals arrested for connections to ISIS has accelerated as recognition of the militant group's brand grows.

The center found that from March to December 2014, before the group held any territory, an average of one US citizen per month was arrested for ties to the organization. But from January 2015 to June 22, 2015, law enforcement arrested an average of 7 US citizens a month for connections to the terrorist group.

These arrests include US residents who are providing or attempted to provide various levels of support for the organization, from helping ISIS recruit via social media to planning domestic terror attacks to trying to leave the country to become a foreign fighter in Syria or Iraq. The majority of those arrested, according to the center, are US citizens in their mid-twenties coming from a broad range of ethnic backgrounds.

Despite law enforcement's success in disrupting and arresting residents suspected of having ties to ISIS, The Soufan Group notes that there is still a large potential pool of suspects and followers of ISIS within the country. ISIS' nebulous nature and willingness to call on individuals to carry out lone-wolf attacks also makes policing against potential plots more difficult.

"These disrupted plots and pre-plots varied widely in scope and threat but they all shared the characteristic of being inspired by the Islamic State rather than being directed by the group," The Soufan Group notes. "Traditional notions of command-and-control do not apply to the Islamic State, leaving traditional methods of law enforcement scrambling to adjust to plots where the fuse is lit not by an order but by an ideology."

The center notes that the major motivations driving US residents to join ISIS are resentment against US policy and feelings of alienation within US society, along with a favorable view of ISIS' military successes.