A new opinion piece written in The Hill by Marik Von Rennenkampf outlines the new definition Congress has taken on UFOs, or as officials would like them to be referred to, Unidentified Aerial Phenomena or UAP.
That naming has since been updated with Congress now revising the definition of a UFO to include "transmedium" objects, which means objects that are capable of transitioning "between space and the atmosphere, or between the atmosphere and bodies of water".
In a previous Congress report, a nation-security-focused committee pointed out a growing number of objects demonstrating technology that allowed them to seamlessly travel between space, air, and water, with the report noting "transmedium threats to United States national security are expanding exponentially."
Congress has now updated its definition of UFO to exclude any "man-made" object, which means that its new UFO offices dedicated to identifying objects of unknown origin will be handing over any unidentified object that appears to be man-made over to a separate office, allowing the UFO offices to purely concentrate efforts on objects that aren't man-made. A congressional directive reads that any object identified as "as man-made...will be passed to appropriate [Department of Defense and Intelligence Community] offices".
As pointed out by Von Rennenkampf, this implies that the newly established UFO offices are focusing on objects that aren't man-made, which by definition, implies there is at least some degree of belief within the US government that there are objects that have already been seen by government officials that can't have a man-made origin. These are the objects that pose a national security risk, hence the focus.
By its own definition, the US government has implied it's searching for UFOs of alien origin, as its UFO offices are not interested in any that are man-made.