FBI Director James Comey said fewer Americans are traveling to fight alongside the Islamic State of Iraq and Syria (ISIS), CBS news reported on Thursday.

He said the group's influence in the United States appears to be on the decline. Comey told reporters at a roundtable discussion Wednesday that the number of Americans who have gone or have tried to join the group has dropped to about one per month. It used to be a half-dozen or more a month.

He said there's "no doubt" that something has happened to diminish the attractiveness of ISIS to Americans.

Comey said last month that the number of people attempting to leave the US to join ISIS has been down for nine months, and that it appeared to be a general downward trend.

Comey said there are a few reasons -- in addition to the group's mounting battlefield losses - that this is likely: the aura and fad that came with the group has faded; prison sentences for supporters and members are piling up; and people are realizing how hellish it is to live in ISIS territory.

The extremist group is under constant pressure and has cut fighters' salaries by about half.

Those circumstances include the dramatic drop in global prices for oil - once a key source of income. Additionally, the targeted airstrikes have dramatically reduced cash stockpiles and oil infrastructure.

Source: MENA