Under US law, countries that have a serious problem with looting / grave-robbing / metal-detecting are allowed to ask for a "Memorandum of Understanding" which lists the kind of artifacts being looted. Currently the US and Italy have one and it covers, among other things, coins of Greek Sicily. So Americans can't just bid in British and German auctions for such coins, because without paperwork showing the coins have been on the collector market for years it is against the law to bring them to the US.
The Italians are asking for an extension. The extensions last for five years. The extension doesn't have to cover the same stuff. It could cover fewer coin types or more coin types. If it covered all Roman Imperial coins it would be frustrating, because these coins would be selling openly in many EU countries, but Americans wouldn't be able to buy them.
Some folks would like to see all ancient artifact sales banned. Others feel the sale of common objects like coins and rings is not a big deal. The purpose of filing comments is so that the US representatives don't just rubber-stamp whatever the Italian representatives ask for.