In a video released Wednesday by the Islamic State, a one-legged fighter identified by the group as an American calls on Muslims in the United States to "take advantage" of the country's gun laws to obtain weapons and carry out attacks.

The fighter, identified by the nom de guerre "Abu Salih al-Amriki," wears khaki fatigues with a holstered pistol in the online video, published by a propaganda wing of the Islamic State. He speaks in English with what sounds like a New York City-area accent.

"Take advantage of the fact that you can easily obtain a rifle or a pistol in America," the fighter says. "Spray the kuffar [infidels] with bullets so that their fear of the Muslims rises and they continue to reveal their hatred towards Islam."

The SITE Intelligence Group, which tracks Islamist militant media, published a copy of the video, in which Abu Salih also calls President Trump a "dog of Rome."

"You entered into the White House on the back of your crusader rhetoric, which the fake media has pressured you to tone down," the fighter says.

The FBI had no immediate comment on the man's identity nor the potential threat of his entreaties to violence. Tyler Houlton, a spokesman for the Department of Homeland Security, said the agency "is aware of numerous online terrorist threats" and routinely works with its partners to analyze threats and respond.

The possibility that Islamic State followers in the United States will acquire powerful weapons by legal means has been a growing concern of American counterterrorism officials.

Last week, the outgoing director of the National Counterterrorism Center, Nicholas Rasmussen, told reporters that U.S. gun laws are undermining efforts to protect the country from mass-casualty attacks.

"We find ourselves in a more dangerous situation because our population of violent extremists has no difficulty gaining access to weapons that are quite lethal," Rasmussen said. "I wish that weren't so."

[Senior counterterrorism official expresses concern about U.S. gun laws]

The video released Wednesday begins with Abu Salih slipping on what looks like a prosthetic leg and pushing himself up on crutches. A bullet-scarred cityscape of demolished buildings appears in the background as he launches into his statement, in which he also urges other wounded and disabled militants to keep fighting. It was not immediately clear where or when the statement was recorded.

The slickly produced video is part of a recent series the Islamist militant group has dubbed "Inside the Caliphate," featuring mainly foreign militants threatening attacks. A montage of beheadings and bombings follows Abu Salih's statement, set to a soundtrack of militants singing "Soldiers of Allah."

The recent videos were produced by the Islamic State's al-Hayat Media Center, which has published some of the group's most high-profile material targeting Western audiences. Its online magazine Rumiyah is published in several languages, including English, and often features calls for attacks in the West.

The group has urged followers to kill with any tools at their disposal, including vehicles, and asserted responsibility for the Oct. 31 truck attack that killed eight people along a bike path in Lower Manhattan. In Wednesday's video, Abu Salih also tells attackers to "get a knife and slice the throat of the [infidels] so that they know that the blood of the Muslims is not cheap."

The group's media output has waned, however, as it loses prime territory in Iraq and Syria where it once declared an Islamic caliphate.

Before Wednesday's release, the most recent installment of the "Inside the Caliphate" series urged Islamic State followers to be patient after the "blood spilled" in Syria and Iraq. It also encouraged supporters everywhere to "rise against the [infidels]."

Erin Cunningham in Istanbul contributed to this report.