(a)  A person who knowingly places, or causes to be placed, in navigable waters of the United States, by any means, a device or dangerous substance which is likely to destroy or cause damage to a vessel or its cargo, cause interference with the safe navigation of vessels, or interference with maritime commerce (such as by damaging or destroying marine terminals, facilities, or any other marine structure or entity used in maritime commerce) with the intent of causing such destruction or damage, interference with the safe navigation of vessels, or interference with maritime commerce shall be fined under this title or imprisoned for any term of years, or for life; or both.

(b)  A person who causes the death of any person by engaging in conduct prohibited under subsection (a) may be punished by death.

(c)  Nothing in this section shall be construed to apply to otherwise lawfully authorized and conducted activities of the United States Government.

(d)  In this section:

(1)  The term “dangerous substance” means any solid, liquid, or gaseous material that has the capacity to cause damage to a vessel or its cargo, or cause interference with the safe navigation of a vessel.

(2)  The term “device” means any object that, because of its physical, mechanical, structural, or chemical properties, has the capacity to cause damage to a vessel or its cargo, or cause interference with the safe navigation of a vessel.