The message comes as the Communist Party faces political resistance in Hong Kong and in self-ruled Taiwan, which Beijing views as a rebel province.
China is also in dispute with it’s Southeast Asian neighbours — including the Philippines — over its South China Sea claims, while a tense border dispute with India is ongoing.
“We will never allow any people, organisation or political party to split any part of Chinese territory out of the country at any time, in any form,” Xi told an audience of party and army officials gathered at Beijing’s Great Hall of the People.
“No one should expect us to swallow the bitter fruit that is harmful to our sovereignty, security or development interests,” he said.
Since coming to power in 2012, Xi has centralised power, cracked down on critics of the party and taken a hard line on territorial disputes.
Beijing is also engaged in a military modernisation programme, and indulging in more frequent demonstations of power — a break from its former policy of “hide your strength”.
At a military parade in Inner Mongolia on Sunday, Xi stressed the need to build a world-class army loyal to the Communist Party — not the people — and capable of “defeating all invading enemies”.
In June, China held one of its largest military parades in decades to mark the 20th anniversary of the former British colony’s handover to China. Observers say this was a pointed message to pro-democracy campaigners in the semi-autonomous city state.
And as we reported in December, the country sailed its first aircraft carrier near Taiwan, where politicians have angered Beijing by refusing to acknowledge that both sides are part of “one China”.
The ship was on its way to the South China Sea, which Beijing has almost-completely claimed as its sovereign territory, despite completing claims by the Philippines and other countries.
Beijing insists that India should withdraw from the area, which is claimed by Bhutan, and has warned that it will step up its troop deployment.
While not a disputed boundary, it has also been reported that substantial numbers of PLA troops are massing along the border of North Korea.