Anti-Japan protests continued across China on Tuesday, with thousands of people marching on the Japanese Embassy to mark the anniversary of Japan’s brutal invasion 81 years ago.

The numbers equaled or surpassed those seen in riots over the weekend, but almost no violence was reported as Chinese security forces turned out en masse to contain demonstrations that authorities had allowed, and even encouraged, a week ago. Even so, several of Japan’s biggest brand-name companies shut down factories in China, and Japanese shops and restaurants closed.

The recent tensions over a disputed chain of islands have threatened to strain the $340 billion trade relationship between China, the world’s second-largest economy, and Japan, the third-biggest. While the Chinese government had seemed willing at first to use the protests to increase its bargaining power in the territorial dispute, Tuesday’s overwhelming show of force signaled that it intends to rein in the demonstrations before they spiral out of control and affect the already slowing Chinese economy.

Outside the Japanese Embassy in Beijing, paramilitary police with riot gear, as well as uniformed and plainclothes officers, flooded the area, setting up a tightly controlled, prescripted protest routine. Protesters were divided into manageable groups of a few hundred, separated by disciplined lines of officers and led in marching and chants by leaders in the front.

A helicopter hovered above for much of the day, while authorities instructed the crowds via loudspeakers to protest “in an orderly manner” and to avoid “impulsive behavior.”

Meanwhile, the diplomatic spat over the islands — called Senkaku by the Japanese and
Diaoyu by China — continued as two Japanese activists landed on one of the islands, provoking angry responses in Beijing.

“The unlawful landing of the Japanese right-wingers on the Chinese territory of the Diaoyu islands was a gravely provocative action violating Chinese territorial sovereignty,” Chinese Foreign Ministry spokesman Hong Lei said in a statement.

At an event with U.S. Defense Secretary Leon E. Panetta, Chinese Defense Minister Liang Guanglie also blamed Japan for triggering the crisis during a politically sensitive time for China, as party officials prepare for a once-
in-a-decade leadership transition.

One unexpected image to surface in Tuesday’s demonstration was that of late party chairman Mao Zedong, in portraits carried by protesters and in Maoist references in chants and on banners. The spectacle of hundreds of Mao portraits held aloft recalled the days of traumatic upheaval during China’s Cultural Revolution and appeared to shock some.

“I don’t know why they are holding up Mao’s picture, to be honest,” said Yang Qingyang, 24, a protester marching in front of the embassy. “I think they are just feeling nostalgic about the past. I’m not into that myself.”

Many protesters said the invocations of Mao were meant to shame current leaders into standing up to foreign powers as Mao once did. However, the presence of those protesters, who seemed to have arrived in a group, also suggested an attempt by the leftist, Maoist wing of the party, among others, to use the anti-Japan rallies as an excuse to advocate for their fallen leader Bo Xilai.

Also Tuesday, the government was conducting the trial of Bo’s chief lieutenant on a range of charges, including defection and abuse of power. And in coming days, the party is expected to announce whether Bo will face expulsion from the party, criminal charges or worse in the wake of China’s worst political scandal in two decades. The confluence of events reflected the competing forces at play in every arena of Chinese politics as its leaders jockey for power in the coming transition.

Cao Zhaojin, a retired worker who acknowledged having brought dozens of cardboard printouts of Mao’s portrait to the protest, cited his admiration of Mao’s tough stance against “U.S. aggressors and all their running dogs.”

“How can we forget Mao’s thoughts that we should despise all our enemies, but that tactically we should take them all seriously?” said Cao, 58.

In the next breath, however, he veered seamlessly into a defense of Bo. “In the history of the party, lots of cadres, including Chairman Mao, they all made mistakes, but everyone deserves a chance to correct the mistake,” he said. “A comrade who has corrected his mistake is still a good comrade.”