The US law that did that that was struck down as unconstitutional more than 14 years ago, so the "is classified" claim is false.

http://www.nytimes.com/2002/04/16/national/16CND-PORN.html

Wrong Law

https://en.wikipedia.org/wiki/PROTECT_Act_of_2003

https://en.wikipedia.org/wiki/United_States_v._Handley

That law currently stands.

PROTECT has been upheld to the extent that it only criminalized virtual explicit child sex content that also met the obscenity test, which -- since obscenity had separately been ruled outside of First Amendment protections irrespective of whether it is factual at all, much less whether or not it contains real images of children, is unsurprising; this distinguished it from previous laws that had been struck down that included blanket band on virtual explicit child sex content. To the extent provisions of it appear on their face to go further, they have been viewed unfavorably by the courts, including being expressly found unconstitutional by the trial court in the Handley case you refer to.

The way obscenity laws in the US and the states work is that these drawn images will always be looked at as obscene.

The standard currently used for obscene is

(a)whether the average person, applying contemporary community standards would find that the work, taken as a whole,appeals to the prurient interest

(b) whether the work depicts or describes, in a patently offensive way, sexual conduct specifically defined by the applicable state law

(c) whether the work, taken as a whole, lacks serious literary, artistic, political, or scientific value

Now, would the 'average American' find lilocon/shotacon to be excessively focused on sex? (yes) would it be found offensive under applicable laws, in this case child porn laws (yes). Would the 'average American' take any random manga as having serious literary or artistic value? (no). So, is lolicon/shotacon illegal? It sure is.

The problem with the above is it is not a measurable standard, it is left up to interpretation, and that interpretation will come down on the side of obscene with anything that is not regarded mainstream. Not that long ago homosexual porn was, and in some states it's still difficult to sell sex toys because of obscenity laws. Obscenity laws are used as an end run around the First Amendment for these cases, as it was here. You can say it wasn't because of the PROTECT Act, but the fact remains he had to plead guilty to possession of shotacon and he was facing the penalties of the PROTECT Act because the court could go ahead and call it obscene to bypass the problem of explicitly calling something illegal.

Images of children engaging in sex, or lilocon/shotacon are considered illegal in the US as kiddy porn, either by the PROTECT act explicitly in jurisdictions outside that courts ruling, or by obscenity laws in general. And that is disgusting because it is a thought crime.

The exception would be Oregon which shot down general obscenity laws in their entirety.