A US woman whose husband was slain in Jordan while serving as a private contractor is suing Twitter, alleging that the micro-blogging company is a "tool for spreading extremist propaganda" that led to her husband's death at the hands of a terrorist last year.

The federal suit (PDF) was filed Wednesday against San Francisco-based Twitter. It claims the service is in breach of the Anti-Terrorism Act, that Twitter "purposefully, knowingly or with willful blindness" provided "material support to the preparation and carrying out of acts of international terrorism, including the attack in which Lloyd Fields Jr. was killed."

The suit claims that for years, "Twitter has knowingly permitted the terrorist group ISIS to use its social network as a tool for spreading extremist propaganda, raising funds, and attracting new recruits. This material support has been instrumental to the rise of ISIS." The suit continues: "ISIS members use Twitter to post instructional guidelines and promotional videos, referred to as 'mujatweets.'”

Twitter said the lawsuit is meritless. Taking a page from Google's PR tactics, the company said it would only provide a response if Ars promised to attribute it to a "Twitter spokesperson" and not to any named Twitter employee.

"While we believe the lawsuit is without merit, we are deeply saddened to hear of this family's terrible loss. Like people around the world, we are horrified by the atrocities perpetrated by extremist groups and their ripple effects on the Internet," Twitter said. "Violent threats and the promotion of terrorism deserve no place on Twitter and, like other social networks, our rules make that clear. We have teams around the world actively investigating reports of rule violations, identifying violating conduct, partnering with organizations countering extremist content online, and working with law enforcement entities when appropriate."

The lawsuit quotes several US government officials that say Twitter has been a tool of terrorists. It also noted a Brookings Institute study from last year.

In that research, Brookings estimated there were up to 70,000 pro-ISIS accounts on Twitter and said 46,000 "is our most conservative" estimate. The report came after the FBI issued a warning about American teens being susceptible to ISIS recruitment tactics. Twitter says it removes tens of thousands of terror-laden accounts and that it removes them after they become aware of them.

Twitter, meanwhile, is likely immune from liability under Section 230 of the Communications Decency Act.

Fields' wife, Tamara, claims in the suit that her husband, a former Louisiana police officer, was contracting with DynCorp International and assigned to the International Police Training Center in Amman, Jordan last year. In November, a terrorist smuggled in weapons and killed five people, including Tamara's husband. The suit, however, does not allege that any chatter on Twitter was directly connected to Fields' death. Instead, it describes a terror-laden message the shooter sent friends via the WhatsApp mobile messaging platform days before Fields was killed.