In 2006 we estimated they had 100 nuclear warheads but that estimate could be as high as 2,000.
The Chinese do not have 2,000 warheads. The source of that information is highly questionable.
And they have the miniaturized W88 H-bomb design captured via espionage. Each W88 is 475 kT, which is about 30 times bigger than the Hiroshima bomb.
That's not how it works.
It's not miniaturized. It's simply a linear implosion design which permits miniaturization. The W48 6"/155mm AFAP, the W70 Mod 3 for the Lance, the W80 for the air, sea and ground-launched cruise missile warheads, and the W85 for the Pershing II all used linear implosion. Note that the W80 and W85 were also variable yield warheads (what the idiot Media calls "dial-a-yield") that could be set from 0.3 kt to 80 kt.
The Chinese did not gain the design plans through espionage. As the
Wall Street Journal reported and a bi-partisan congressional committee that investigated the matter stated:
"Beijing has stolen U.S. design data for nearly all elements needed for a major nuclear attack on the U.S., such as advanced warheads, missiles, and guidance systems. Targets of the spying ranged from an Army anti-tank weapon to nearly all modern fighter jets. Most wasn’t done by professionals, but by visitors or front companies. Lax security by the Clinton Administration is blamed in part, and satellite makers Hughes and Loral are criticized."
Although China obtained the design, the plans were useless unless the Chinese could conduct tests to ensure the design actually works.
Clinton actually gave the Chinese not only all of the US nuclear weapon test data, but also a Cray supercomputer to analyze the data and model test detonations, which in theory would avoid the need to conduct any nuclear weapons tests.
Clinton later attempted to justify his actions by claiming that it would result in the Chinese reducing their warhead yields. That is true to some extent. Large yields were necessary in the past because of poor accuracy of the missiles. Better technology, especially better satellite technology, has increased the accuracy of warheads and both Russia and the US have switched to lesser warhead yields because of it.
Even so, there's no evidence China has made any modifications to any of their warheads, which are estimated to be in the 1 Mt range.
If China ever engages in a modernization of its nuclear warheads, perhaps it will use the design and reduce its warhead yields.