WASHINGTON, Sept. 2  -- A new video surfaced Tuesday, appearing to show the beheading of Steven Sotloff, a second American, by a self-professed member of the Islamic State (IS), media here reported.

According to reports, in the video, which appeared online on Tuesday, Sotloff told the camera: "I am sure you know exactly who I am by now and why I am appearing."

The video then cut to the militant who said as long as U.S. missiles "continue to strike our people, our knife will continue to strike the necks of your people," said the reports.

At a briefing at noon Tuesday, White House Press Secretary Josh Earnest said he has not seen those reports yet and "I am not in a position to confirm the authenticity of that video or the reports at this point."

He also noted that the United States has dedicated significant time and resources to trying to rescue Sotloff and the administration has obviously been watching very carefully, since this threat against Sotloff's life was made a few weeks ago.