The US Navy invited China to participate in "Rim of Pacific" (RimPac) naval exercise this month. This is an international deal, with every Pacific country and some Atlantic countries to sending ships to play wargames. The Chinese sent a pair of their latest and newest destroyers which impressed everybody with their phased array radars, vertical launch missiles, 100mm gun, good paintwork, and sharp looking crews. The Chinese were clearly showing off, they allowed tourists on board while they were in port, and they allowed an Aviation Week reporter to sail with them. The westerners were duly impressed. The phased array radars suggest that the Chinese have a ship borne SAM system as good as the US Aegis system. Aegis is very good, and the Chinese might have matched it. We cannot tell for sure with out looking at the missile hit rate from live firing trials, information which is top secret in any Navy.
Aviation Week was impressed by the 100 mm (4 inch) cannon carried by the Chinese. The US Navy only carries a 76 mm (3 inch) gun. I am not so impressed, WWII US destroyers carried a battery of six 5 inch guns. Granted that modern warships rely upon their missiles to take out aircraft and surface vessels, there is a need for guns, for use against shore targets and to convince enemy merchantmen to heave to and be boarded. You can't really use missiles against a recalcitrant merchie, a missile hit will sink him. Where as the traditional shot across the bow, possibly followed with a few rounds to the bridge will get their attention every time. Gun rounds are smaller than missiles and a ship can carry more of them.