Normally, China's DF-5 ICBM carries a 5 megaton thermonuclear warhead.
From the nation.time.com
The R-12 was the first operational intermediate-range ballistic missile, the first missile ever mass-produced, and the first Soviet missile deployed with a thermonuclear warhead.
From the en.wikipedia.org
Most thermonuclear weapons are considerably smaller than this, due to practical constraints from missile warhead space and weight requirements.