While the backstory of the character has never been delved into deeply in the previous versions of the story, there has never been much indication that the government organization that she worked for, called Section 9, had any intentions beyond upholding the law.
It’s possible of course, that the trailer is using editing to intentionally mislead the audience in order keep the surprise.
While the first half of that story, showing a technology based enemy, falls in line with what fans of Ghost in the Shell would be expecting to see, the other part of the trailer, which had been hinted at previously, seems to include the idea that the creation of The Major was not done as a way to save her, as she believed, but instead was potentially done against her will.
Ghost In The Shell (2017) - Official Trailer - Paramount Pictures