According to a White House response sent to Congress about the rationale that the US is not engaged in a war with Libya and is therefore unhindered by any legislative restrictions placed on it by the 1973 War Powers Resolution:

U.S. operations do not involve sustained fighting or active exchanges of fire with hostile forces, nor do they involve the presence of U.S. ground troops, U.S. casualties or a serious threat thereof, or any significant chance of escalation into a conflict characterized by those factors…

The same could be said about a US nuclear strike on any country unable to mount a similar response. Just planning ahead.