China poses most serious threat to US: Top general

China poses the most serious threat to the national security of US in the long run, a top American general told the country's lawmakers.

"I think China is the main challenge to the US national security over the next 50 to 100 years," General Mark A Milley, said on Thursday in his confirmation hearing for Chairman of the Joint Chiefs of Staff.

"I think some historian in 2119 is going to look back at this century and read a book and the central theme of the story is going to beat the relationship between the United States and China,” Milley said responding to a question from Senator David Perdue.

Milley agreed with Perdue that China was using trade as leverage to achieve its national security interests and the one belt road initiative was a part of it.

"With regard to their belt-road initiative and there made in China 2025, my experience is that they generally don't tell their adversaries what they are going to do unless they have made a determination that they either don't have the wherewithal or the will to stop them," Perdue said.

The Georgia Senator expressed his concern over Chinese investments in ports around Africa and the Indian Ocean but also in South America where there are over 50 port investments that they have made with proprietary loans.

"Now see in Colombo, Sri Lanka and then also Karachi and Pakistan where they have actually foreclosed and are now militarising those two ports in addition to what they have done in Djibouti," he said.

Milley said that China has expanded throughout all of the regions of the globe and they are clear competition, they are primarily in competition for resources in order to build and improve their military in order to fund and feel their economy.

"I think that what we need to do is to uphold the norms of the international order that has been in place for the last seven decades," he said.

Responding to another question, he said there is anxiety and fear among the countries due to an aggressive China and they want the United States there.

"They want us there as a security partner, they want us there as a security guarantor, they want full presence forward presence. They believe that we are a force of stability and there is great concern," he said.

China, though he noted is not an enemy of the United States.

"I want to make that clear. They are an adversary, I would say, they are our competitor. But that's different than an enemy. An enemy in military language means they are in an active armed conflict. You are at war. We're not there. We don't want to be there," Milley said.

"We want peace, not war with China. But having said that, I think that the best way to do that is to make sure that we are prepared. China is improving their military very, very rapidly... they are outspending us in research, development and procurement. You would never think that but they are," he said.

"The United States need to make sure that we do not lose our advantage that we have relative to other countries specifically to China," Milley said.

"China went to school on us. They watched us very closely in the first Gulf War, the second Gulf War, they watched our capabilities. And in many, many ways they have mimicked those and they have adopted many of the doctrines in the organisations, etc.," he told the lawmakers.

Reiterating that China has already militarised the South China Sea and have capabilities in air, sea and ground to influence surface sea operations, Milley asserted that freedom of navigation operations is critical to ensure that the Asia Pacific region remains free and open to commercial access.