Here:

TITLE 18 > PART I > CHAPTER 113B > § 2331
§ 2331. Definitions

(1) the term “international terrorism” means activities that—
(A) involve violent acts or acts dangerous to human life that are a violation of the criminal laws of the United States or of any State, or that would be a criminal violation if committed within the jurisdiction of the United States or of any State;

(B) appear to be intended—

(i) to intimidate or coerce a civilian population;
(ii) to influence the policy of a government by intimidation or coercion; or
(iii) to affect the conduct of a government by mass destruction, assassination, or kidnapping; and

(C) occur primarily outside the territorial jurisdiction of the United States, or transcend national boundaries in terms of the means by which they are accomplished, the persons they appear intended to intimidate or coerce, or the locale in which their perpetrators operate or seek asylum;

Notice the line: involve violent acts or acts dangerous to human life. Looks to me is all they would have to do is prove that Assange was engaged in “acts dangerous to human life”. Let it be noted that AG Holder and Admiral Mullin have both repeated on several occasions that Assange’s acts where potentially dangerous to human lives (i.e. solders, foreign service personnel, etc.).