((a)) ** .—** Whoever kills a national of the United States, while such national is outside the United States, shall—
((1)) if the killing is murder (as defined in section 1111(a)), be fined under this title, punished by death or imprisonment for any term of years or for life, or both;
((2)) if the killing is a voluntary manslaughter as defined in , be fined under this title or imprisoned not more than ten years, or both; and
((3)) if the killing is an involuntary manslaughter as defined in , be fined under this title or imprisoned not more than three years, or both.
((b)) ** .—** Whoever outside the United States attempts to kill, or engages in a conspiracy to kill, a national of the United States shall—
((1)) in the case of an attempt to commit a killing that is a murder as defined in this chapter, be fined under this title or imprisoned not more than 20 years, or both; and
((2)) in the case of a conspiracy by two or more persons to commit a killing that is a murder as defined in , if one or more of such persons do any overt act to effect the object of the conspiracy, be fined under this title or imprisoned for any term of years or for life, or both so fined and so imprisoned.
((c)) ** .—** Whoever outside the United States engages in physical violence—
((1)) with intent to cause serious bodily injury to a national of the United States; or
((2)) with the result that serious bodily injury is caused to a national of the United States;
((d)) ** .—** No prosecution for any offense described in this section shall be undertaken by the United States except on written certification of the Attorney General or the highest ranking subordinate of the Attorney General with responsibility for criminal prosecutions that, in the judgment of the certifying official, such offense was intended to coerce, intimidate, or retaliate against a government or a civilian population.