WASHINGTON (AP) – The U.S. military commander in charge of defending the U.S. homeland said Tuesday that he believes there are al-Qaida cells in the United States or people working to create them.

Air Force Gen. Victor “Gene” Renuart said that while the terrorism threat within the nation’s boundaries has increased in the past year, officials have strengthened intelligence sharing, particularly in an effort to shore up weaknesses in security at U.S. ports.

“I believe there are cells in the United States, or at least people who aspire to create cells in the United States,” Renuart said in an interview with The Associated Press. “To assume that there are not those cells is naive and so we have to take that threat seriously.”

He added, “Am I concerned that this will happen this summer, I have to be concerned that it could happen any day.”

Renuart, who took over the job as the head of U.S. Northern Command in April, said that to counter the growing threat, the military also needs to create two more brigade-size units to be available to respond to nuclear, chemical and biological incidents at home – because currently there is only one. A brigade is about 3,500 troops.

Renuart’s comments came in the wake of a national intelligence report released last week, which concluded that al-Qaida is using its growing strength in the Middle East to plot attacks on U.S. soil.