TOKYO -- The question of how to deal with China has always been complicated and it is becoming more so.

The reason is that even as China grows stronger, the contradictions of the country's one-party rule are likely to become more serious and the country more internally unstable. If this happens, the Chinese leadership may have difficulty controlling the far-flung organs of government, which may sometimes behave recklessly. The world must therefore be prepared to face a China that is simultaneously powerful and fragile.

The ruling Communist Party gives the impression that its leadership has tightened its grip over the country. President Xi Jinping has succeeded in bringing down his political rivals through an anti-corruption campaign and removing limits on his term of office. He can remain in power indefinitely.

The power struggle in the upper reaches of the party has played itself out and Xi has no challengers. However, the party has only about 90 million members, a small fraction of the population. Xi has the party speaking with one voice, but that does not mean he has won the hearts of China's 1.4 billion people.

Xi Jinping speaks at the closing session of the National People's Congress in Beijing in March. © Reuters

There are growing problems in Chinese society that could weaken the government's ability to hold the country together: enormous economic disparities, endless corruption and smoldering discontent in the Xinjiang Uighur Tibet autonomous regions to name a few.

While China has grown stronger economically and militarily, its internal problems remain serious. The question is how this will influence its relations with other countries. One neighbor looking on anxiously is India, which fought a war with China in 1962 and still has border disputes with Beijing. In late February, a forum was held in New Delhi, with Japanese, Indian and European experts in attendance. I was at the meeting and sensed the Indians were very anxious about the rise of China.

China is trying to develop an international order that put it at the apex by making the most of its capabilities in information technology, as well as its military and economic power. Indian participants in the forum expressed concern that China's Belt and Road Initiative could accelerate this trend.

India's concerns about China are not new. What is new is that it fears not only China's strength, but also its brittleness.

On another occasion, I heard an interesting story from an Indian diplomat.

In September 2014, Xi visited India for the first time as president to call for friendship between the two countries. Several days earlier, something incredible happened: In India's Ladakh region, where the boundary with China has not been settled, more than 1,000 Chinese troops suddenly crossed into Indian-controlled territory and stayed there during Xi's entire visit. There were rumors that Xi had authorized the incursion to pressure India, but that was apparently not the case.

Indian Prime Minister Narendra Modi welcomed Xi on his arrival and had a private conversation with him ahead of their official talks the following day. According to the diplomat, their conversation went something like this:

Modi: "Today is actually my birthday, but I never thought I would receive such a present."

Xi: "What do you mean?"

Modi: "Don't you know that your troops have crossed the border and moved on to the Indian side?"

Xi: "I will check into it and let you know by tomorrow."

The diplomat said Xi looked genuinely bewildered by Modi's explanation of the situation.

According to the official, Xi promised Modi during their meeting the following day that he would settle things when he returned to Beijing. As promised, Chinese troops pulled out of Indian territory a few days after Xi's return.

If this account of events is correct, it suggests Xi was unaware of the incursion. Rumors swirled at the time that an army faction disloyal to Xi sent a unit over the border knowing it would embarrass the Chinese leader.

In the three and a half years since, Xi has steadily tightened his grip on the military. But in the process he has ousted a number of senior officers, probably causing much resentment.

In June of last year, Chinese troops began building roads along the border between China and Bhutan without notice, prompting India to send troops to Bhutan at the latter's request. The ensuing military standoff dragged on for two and a half months.

In the end, a meeting between Xi and Modi defused the situation. Sources in India said exchanges with China convinced Indian leaders that the road building was not ordered by leadership in Beijing but by people on the ground.

No matter how strong Xi's position is within the Communist Party, it is difficult for him to control every everything that happens in China. Masanori Nishi, Japan's former administrative vice minister of defense, argues that China growing assertiveness on the global stage is based on it economic clout. But, he cautions, historically, Chinese dynasties have collapsed every 200 to 300 years, to be replaced by a new one.

"If China enters such a phase again in the future," Nishi said, "the domestic turmoil will likely have a huge impact on the country's foreign policy."

This scenario, he said, "will cause more trouble for the world."

At times the Chinese military has taken actions that have caught Japan and the U.S. off guard. In some cases, the military may have been acting on its own. "Due to a lack of control by the commander-in-chief, those farthest from the center have committed provocative acts in some cases," said a Japanese national security official.

This unpredictability is apparent in other areas as well. If Chinese society becomes unstable, the Xi government will have its hands full dealing with domestic problems and may be tempted to take a harder line with other countries diplomatically and economically. That would make dealing with China harder for its neighbors, and might worry them more than China's growing might.