If China were to assert more pressure on North Korea to suspend its nuclear and missile programmes, it would not be at the behest of United States President Donald Trump.

Rather it would be because North Korea's development of nuclear weapons poses an immense threat to China, Professor Jia Qingguo, dean of the School of International Studies at Peking University, said recently.

The view of several analysts, both within and outside China, is that Beijing is already adjusting its North Korea policy because of this and other reasons.

The shift has been evident in recent months, in Beijing's decision to back heavier sanctions against Pyongyang by the United Nations Security Council (UNSC) and the steps it took to more fully implement existing sanctions. That is significant because China had in the past expressed "reservations over the sanctions and even objected to some of them", said security analyst Wang Xiangsui of Beihang University.

Security analyst Li Mingjiang of the S. Rajaratnam School of International Studies at Nanyang Technological University summed up the change as one of emphasis. Whereas in the past, Beijing placed greater emphasis on regime survival in Pyongyang and stable relations with its close neighbour and less on denuclearisation of the Korean peninsula, it now places equal emphasis on the two, he said.

But why has Beijing adjusted its stance now when Pyongyang's nuclear ambitions have been clear for years?

From hope to reality

A key factor tilting the balance is how North Korea's desire for nuclear weapons and missiles has in recent years gone from mere hope to concrete fact. Pyongyang has conducted five nuclear bomb tests to date, and is said to be getting close to building nuclear warheads small enough to mount on missiles. It has also tested ballistic missiles with increasing frequency and success.

Professor Wang said it is now obvious that North Korea possesses nuclear weapons and "China has no room to be ambiguous".

"It needs to express its stand clearly, that it opposes the North's possession of nuclear weapons and wants it to give them up," said Prof Wang.

The possibility that Japan and South Korea will follow suit by arming themselves with nuclear weapons as protection against the North, would also work against China's interests.

Another factor causing Beijing to recalibrate its North Korea policy is external pressure, noted Associate Professor Li. China's ties with South Korea have deteriorated as Seoul thinks Beijing is not doing enough to rein in the North. That has led to Seoul aligning itself more closely with the US.

The US for its part has used the North Korea nuclear issue to justify enhanced military deployment in North-east Asia, said Prof Li. An example is the deployment of the Terminal High Altitude Area Defence (Thaad) system, an advanced anti-missile system, in South Korea, he added.

China vehemently opposes the deployment of Thaad on the Korean peninsula because it believes the system's powerful radars undermine its security interests. It has reportedly used various measures to discourage Seoul from deploying Thaad, including reducing the number of Chinese tourists going to South Korea, blocking Korean music videos on streaming services, and closing several of Lotte's stores in China supposedly for breaching fire regulations. Korean conglomerate Lotte had turned over its land to be used for Thaad.

With South Korea due to hold a presidential election next month, the Thaad system now hangs in the balance although deployment has begun.

China is worried that Thaad could also be deployed in Japan.

As tensions on the Korean peninsula rose in recent months, the Chinese sought to revive diplomatic efforts to resolve the crisis. Last month, Beijing called on the US and South Korea to suspend their large-scale military exercises and for the North to halt its nuclear and missile tests, so that both sides could come to the negotiating table in multilateral talks.

Beijing has also suggested a two-track approach of negotiating denuclearisation and a peace treaty simultaneously.

There has been little progress to date on this front.

It does not help that China's own ties with North Korea have deteriorated since Mr Kim Jong Un came to power in 2012, said Prof Li. Mr Kim launched a series of political purges whose targets included his uncle Jang Sung Taek, who had been China's main interlocutor.

In power for five years, Mr Kim has yet to meet Chinese President Xi Jinping or travel to China.

China's next steps

If Pyongyang continues to disregard Beijing's calls to halt its nuclear and missile tests, the latter could put more economic pressure on the North, said Chinese analysts such as Prof Wang.

North Korea's bilateral trade with China now accounts for about 90 per cent of its total trade. It is also almost entirely dependent on China for the oil that keeps its economy going as well as for food and other essential goods.

The tougher measures at China's disposal include tightening up on trade, cross-border activity and finance, which will increase hardship on North Koreans but are unlikely to cause the collapse of the Kim Jong Un regime.

China had in February announced that it would halt all coal imports from North Korea for the rest of the year. Coal is estimated to make up some 40 per cent of North Korea's exports to China and coal exports are a vital source of foreign exchange for Pyongyang.

Still, these punitive measures are likely to stop short of acts that could cause the Kim regime to collapse. That is because Beijing wants to keep North Korea as a strategic buffer zone against the US, which has a military presence in South Korea. A regime collapse in Pyongyang could mean reunification of the two Koreas, with the possibility of American presence at the Chinese border.

Moreover, North Korea is a socialist state and China may not want to see the disappearance of such a comrade in arms, said Prof Li.

He is optimistic that with the concerted efforts of the Chinese squeezing the North Koreans economically and the US putting immense military pressure on them,Pyongyang may be compelled to at least freeze its nuclear and missile programmes.

This could take a few months, he said, as economic measures need time to take effect.

Even if Pyongyang is reluctant to suspend the programmes, they could be significantly slowed down for want of funds and supply of parts and technology, he said. That would be a small step forward.

But some like Prof Jia are more pessimistic. Achieving a nuclear-free and turmoil-free Korean peninsula may be difficult given that North Korea has refused to cooperate.

"In the end, China may have no choice but to assert even greater pressure - even if it means instability or regime collapse," said Prof Jia.