Tests of the weapon, described as “the ultimate doomsday” devices, were successful, meaning DF-17s could be operational by 2020, US intelligence sources believe.





Now experts believe China could use the weapon to take out a US anti-missile system known as THAAD, or Terminal High Altitude Area Defence.





The US installed the THAAD system in South Korea to protect the nation against the threat of a nuclear attack by North Korea.





But China fears that the US, under the presidency of Donald Trump, may use THAAD to launch its own strike should war break out.