China never allows any act that challenges the bottom line of "one country, two systems", Chinese President Xi Jinping reiterated in an important speech on the current situation of China's Hong Kong Special Administrative Region (HKSAR) he delivered on Nov.14 when attending the 11th BRICS Summit in Brasilia, capital of Brazil.

The radical violent activities in HKSAR seriously challenge the "one country, two systems" bottom line, Xi pointed out, stressing that any illegal and criminal activities that challenge the "one country, two systems" bottom line must be severely punished in accordance with law.

Constantly enriching and developing the practice of the "one country, two systems" principle and maintaining long-term prosperity and stability of HKSAR is an important part of the Chinese Dream and an inevitable requirement for improving and developing the system of socialism with Chinese characteristics and advancing the modernization of China’s governance system and capacity.

Over the past more than 5 months, Hong Kong has undergone continuous violent activities which have happened and been escalated at the instigation of Hong Kong's opposition and interference by external forces.

Some people openly preached "Hong Kong independence", chanted "Liberate Hong Kong, the revolution of our times", and defaced the national flag and national emblem of China as well as the regional emblem of HKSAR.

Radicals have even surrounded and attacked the offices of the Central Government in Hong Kong, the Legislative Council building in Hong Kong, and government offices of the HKSAR, attempting to trap Hong Kong in chaos and disable the HKSAR government.

These violent protesters aim to seize control of the HKSAR and turn Hong Kong into an independent or semi-independent political entity, thus ultimately making the "one country, two systems" principle nothing but a concept.

Today, China is faced with a battle between people who are determined to defend the "one country, two systems" principle and forces who try to sabotage the principle, and there is no middle ground or room for compromise on the issue concerning China's sovereignty and the future of HKSAR.

The "one country, two systems" principle is a pioneering initiative that has no precedent to follow. It has been a major issue for the Chinese central government and represents a significant turning point of Hong Kong and its citizens.

Numerous facts have demonstrated that the "one country, two systems" principle is the best solution to the historical question of Hong Kong and the best institutional arrangement to ensure Hong Kong’s long-term prosperity and stability after its return. The "one country, two systems" formula has proved to be a workable solution welcomed by the people.

Meanwhile, as an institutional innovation, the "one country, two systems" national governance principle needs to stand the test and be constantly improved in practice.

The disturbances triggered by the revision of the extradition bill in Hong Kong during the past few months have revealed some deep-seated problems and issues in such fields as politics, economy, and society of Hong Kong, and further highlighted the necessity and urgency of improving the governance systems of Hong Kong.

Fully and faithfully implementing the guideline of "one country, two systems" and constantly improving the institutional system of the "one country, two systems" principle is not only in line with the general pattern of the development of political systems, but is bound to help the ship of the "one country, two systems" principle sail forward steadily.

"One country, two systems" is a complete concept, which should be particularly understood by all. As Xi said, "one country" is like the roots of a tree, and for a tree to grow tall and luxuriant, its roots must run deep and strong.

There are certain bottom lines one shall never touch in the full implementation of the guideline of "one country, two systems".

Any attempt to endanger China's sovereignty and security, challenge the power of the Central Government and the authority of the Basic Law of the HKSAR or use Hong Kong to carry out infiltration and sabotage activities against the mainland is an act that crosses the red line, and is absolutely impermissible.

Anyone and any force should never underestimate Chinese Central Government and Chinese people’s will and resolve to safeguard China’s national sovereignty, security, unity, and the prosperity and stability of HKSAR.

Any attempt to challenge the above-mentioned bottom lines and disrupt or sabotage China’s "one country, two systems" principle will be proven to be in vain and a complete failure.

As Chinese people always say, there would always be a rainbow after the rain. It is firmly believed that with the Central Government and 1.4 billion Chinese people always having its back, Hong Kong will certainly overcome any risk and challenge.

Hong Kong is bound to continue marching forward steadily along the right track guaranteed by the guideline of "one country, two systems" and the Basic Law of the HKSAR, and jointly create a better tomorrow for the Chinese nation together with the Chinese mainland.