The expansion by one brigade for China's DF-31A ICBM per year is normal. See citation from Britain`s International Institute of Strategic Studies below from the year 2010.
Assuming the expansion of China's DF-41 ICBM by 1 1/2 brigade per year is also reasonable, because China's nominal GDP ($11.4 trillion) is almost double the size of its nominal GDP in 2010 ($6 trillion).
China and START. Missile buildup may surpass U.S., Russia as they denuclearize
"China and START
By Richard D. Fisher Jr.,
The Washington Times,
20 September 2010
...
In its latest report to the Congress on China`s military released on Aug. 16, the Pentagon says there are less than 10 DF-31 and "10-15" DF-31A ICBMs, up to five more than reported in the previous year`s report, covering 2008. However, in the 2010 issue of "Military Balance,"
Britain`s International Institute of Strategic Studies notes there is one brigade of 12 DF-31s and two brigades or 24 DF-31A ICBMs, indicating a possible increase of one new brigade from 2008 to 2009."
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A larger military budget does imply a larger thermonuclear arsenal. For example, China fired 10 medium-range DF-21 ballistic missiles in ONE exercise as a show of force. The DF-21 is thermonuclear-capable.
China Flight-Tests 10 DF-21 Missiles | The Washington Free Beacon
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It is widely known that China's DF-41 ICBM can carry 10 MIRVs to overwhelm a missile defense system.
DF-41 | Deagel
"In July 2014 China officially confirmed the development of the DF-41 next generation ICBM with a range of 12,000 kilometers and 10 MIRVed warheads as a direct response to US missile defenses such as THAAD."
China Tests Powerful New Long-Range Nuclear Missile That Could Destroy A Major U.S. City In 30 Minutes | National Security
“As with previous MIRV tests, the PLA has used a small number of reentry vehicles to mask the real capability of the DF-41, which is estimated to be able to loft up to 10 warheads,” said Fisher.
China Flight Tests New Multiple-Warhead Missile | The Washington Free Beacon
"The DF-41 is assessed by U.S. intelligence agencies to be powerful enough to deliver between six and 10 warheads up to 7,456 miles—far enough to reach every corner of the United States from launch areas in eastern China."
