plawolf
Lieutenant General
China does not require 052D based LACMs to put Hanoi within the range of LACMs... TEL based LACMs based even 500 km away from the border would be capable of putting Hanoi in range and then some.
Also, 052Ds already are in service with the SSF -- the SSF's 2nd destroyer flotilla would be the first to have a full destroyer division of four 052Ds in the entire Navy anyway. But I think it is unlikely that Vietnam or any other nation will protest at the deployment of 052Ds even if/when it is confirmed that they can fire LACMs.
Sea based LACMs does have the advantage of having to spend minimal time over enemy territory.
Missiles flying across the land boarder would have to fly pretty much the entire journey over enemy territory, giving them at least the possibility of intercepting them. Especially since the enemy would know the general direction the missiles would be coming from, so have all their sensors and weapons pointed in that direction and can mount multiple layers of defences.
With missiles coming in from the sea, the length of time spent over hostile territory is cut to a fraction, significantly reducing the opportunity for an enemy to try and intercept them.
In addition, with a naval strike, the missiles could be coming in from almost any vector, so would make it far harder to establish the same kind of coverage as is possible with the land boarder.
However, depending on the range of the missiles, it's also perfectly possible for land based missiles to fly a circumspect course over the sea and flank enemy defences.