Editor's note: The Ministry of Defense has confirmed that China is building a second aircraft carrier. Zhang Junshe, a researcher at the PLA Naval Military Studies Research Institute, shares his views on the development with China Daily's Zhang Zhouxiang:

Question: What are the major differences between China's second aircraft carrier and the first?

Answer: The hull of China's first aircraft carrier Liaoning was purchased from overseas, although its engine, power distribution system and weapons are all China-made.

The second one will be fully "designed and made in China" and set a milestone in Chinese navy history. The trial and operation of the Liaoning have provided precious experiences, which help the designers and engineers to avoid some common problems in building an aircraft carrier.

Q: Is a second aircraft carrier necessary for China? How many does China need?

A: Yes, because one aircraft carrier is not enough to meet the defense needs of a large country like China. Aircraft carriers have to undergo regular checks and trials, and some times even repairs. Therefore, a country like China theoretically needs at least three aircraft carriers to ensure one is always in operation. For example, neighboring India has three aircraft carriers.

As a country with 1.37 billion people, more than 18,000 kilometers of coastline, about 3 million square km of maritime territory and increasing overseas interests, China certainly needs three aircraft carriers. Those hyping up the "China threat" theory need to look at China's reality.

Q: How big will the new aircraft carrier be? And why will it use conventional instead of nuclear power?

A: Middle sized. Aircraft carriers can be divided into four categories according to their tonnage. China's new aircraft carrier will displace about 50,000 tons of water without loading and possibly 60,000 tons when fully loaded, which makes it a mid-sized aircraft carrier.

Building a nuclear-powered aircraft carrier involves many concerns: security, preventing nuclear leaks and the replacement of the nuclear reactor after it expires in 15 years. China has technologies to use nuclear power in submarines, but it needs more research to do so in an aircraft carrier.

Q: What are the technological prerequisites for building an aircraft carrier?

A: It takes more than money to build an aircraft carrier. Without mature shipping, aviation, weapon, electronics and communications industries, a country cannot build an aircraft carrier. If a country wants to build a nuclear-powered aircraft carrier, it should also have good nuclear industrial capabilities. And since an aircraft carrier carries thousands of military personnel and covers long distances, the country needs a powerful strategic logistics industry, too.

Q: How long does it take to build an aircraft carrier?

A: That varies from country to country. Having built aircraft carriers for decades, the United States has advanced technologies and rich coordination experience, so it takes about three years for it to build an aircraft carrier, another two years to install weapons and other devices, and about one more year for its military personnel to get used to it. Thus a US aircraft carrier needs about six years to become a truly fighting unit.

For China, there is yet no schedule because we are still accumulating experience in the building process. But we are sure China is making progress and in the future it will take less time to build an aircraft carrier.

Q: How will the new aircraft carrier's role be different from the Liaoning?

A: The Liaoning is more like a training ship, used for the training of personnel, experimenting with new models of planes, and testing the reliability and compatibility of various systems. The new aircraft carrier is supposed to be a truly fighting unit.

Q: How far is China from becoming a genuine naval power now that it is building a second aircraft carrier?

A: Frankly speaking, there is still a large gap between China and global naval powers such as the US. The US has 10 aircraft carriers and the UK will have two new ones in a few years. So even after its second aircraft carrier is commissioned, China will still be far from being a global naval power.

Besides, both the Liaoning and the under-construction vessel are mid-sized aircraft carriers with conventional instead of nuclear-powered engines. So it's too early to say when China will become a global naval power.