The Islamic State's English-language reach on Twitter has stalled in recent months amid a stepped-up crackdown against the extremist group's army of digital proselytizers, according to a study being released on Thursday, February 18, Reuters said.

Suspensions of English-speaking users affiliated with Islamic State from June to October 2015 have limited the group's growth and in some cases devastated the viral reach of specific users, according to the report from George Washington University’s Program on Extremism, which analyzed a list of accounts promoted by the militant group.

The report found that easily discoverable English accounts sympathetic to Islamic State was usually under 1,000, and that those users’ activity was mostly insular, limited to interacting with each other. Islamic State has seized control of wide swaths of Iraq and Syria and claimed credit for attacks in Paris in November that killed 130. The U.S. and other governments consider it a terrorist organization.

Twitter Inc has long been criticized by government officials for its relatively lax approach to policing content, even as other Silicon Valley companies like Facebook Inc began to more actively police their platforms.

Under intensified pressure from the White House, presidential candidates and some civil society groups, Twitter announced earlier this month it had shut down more than 125,000 terrorism-related accounts since the middle of 2015, most of them linked to the Islamic State group.

J.M. Berger, a co-author of the report, said Twitter is still less active than many of its rivals but that part of that is due to its relative youth as a company.

“Each company has been dragged into this kicking and screaming,” he said in an interview, according to Reuters.

Reporting of Twitter accounts affiliated with Islamic State is a steady, low-level activity generally, but occasionally events lead to “periodic purges,” Berger said.