Cases of homegrown terrorism in the United States rose for the second consecutive month, with at least five people arrested or convicted in June of attempting to launch attacks on behalf of the Islamic States and al Qaeda, according to a new congressional report.

The five percent increase in jihadist incidents from May brings to 157 the total number of cases related to homegrown terrorism across 30 states since 2013, the House Homeland Security Committee found in its monthly report on terrorism in America.

"Cases of homegrown Islamic extremism in the U.S. continue to be an issue of concern," according to the committee report, which tracked the first uptick in this type of activity in June following five months of stagnation.

Rep. Michael McCaul (R., Texas), who chairs the Homeland Security Committee, has said despite the collapse of ISIS's self-proclaimed "caliphate" in Iraq and Syria, the group maintains the capability to conduct external operation and remains a threat to the United States and its allies.

At least six plots were foiled in Europe over the same period.

On July 6, two Americans were sentenced on terrorism charges. Aaron Daniels, 21, was sentenced in Ohio to 80 months in prison for attempting to provide material support for ISIS after sending funds to the terrorist group to demonstrate his support. Sean Duncan, 22, was found guilty in Virginia of obstructing a counterterrorism investigation and sentenced to 20 years in prison.

A few weeks later, two would-be jihadists pleaded guilty in California and New York to attempting to provide material support to ISIS. Another was arrested on July 2 in Ohio for attempting to provide material support to al Qaeda.

Violent extremists hoping to attack the United States from within remain a top concern for the FBI in 2018.

The report also highlights the ongoing threat posed by jihadists across the world. This threat came to fruition on July 30 when four international cyclists, including two Americans, were killed after being struck by a vehicle, stabbed, and shot in Tajikistan.