To wander through Vladivostok is to quickly understand why the tariffs are provocative. The people delight in driving used cars from Japan, which is only 500 miles away, saying that they are of far higher quality than Russia’s domestic models.

As a result, the streets offer a jarring sight: used Toyotas, Hondas and other Japanese vehicles, with steering wheels on the right side (in Japan, cars are driven on the left), being driven on the right side of the road. It is unusual to see a car with a Russian brand.

When the economy was surging, Mr. Putin’s government had widespread support, and the opposition was marginalized. Now that times are tough, events in the Far East suggest broader rumblings. And senior officials are no doubt aware that this maritime region, which borders China and North Korea, has historically been prone to political instability because it is so far from Moscow.

The tension has shown no signs of diminishing, and in late January, another demonstration in Vladivostok drew more than 1,000 people. The Communist Party, seeking to capitalize on the tariff issue, joined in. Marchers chanted, “Resign, Putin!” and held up caricatures of Mr. Putin, the prime minister, and President Dmitri A. Medvedev.

The car dealers’ demonstrations in Vladivostok in the past two months have drawn thousands of people, more than events sponsored anywhere in Russia by liberal opponents of Vladimir V. Putin. The government grew so alarmed in late December that it took the extraordinary step of sending special riot police officers to Vladivostok from Moscow, nine hours away by plane, to break up one rally.

Some participants were beaten and briefly arrested, and others said that they had recently received menacing phone calls from the security services ordering them to stop criticizing the government.

Senior officials have portrayed the organizers as nefarious profiteers controlled by foreign agents who want this region to secede from Russia. Behind the scenes, though, it appears that the Kremlin is concerned that resentment over the tariffs will continue to spread from the car dealers to the general population — and turn into a bigger backlash over the government’s handling of the financial crisis.

A vice governor, Yevgeny V. Khokholkov, accused auto dealers of trying to lure people to protests by spreading false rumors that cars with right-hand steering wheels would be banned. He said the Moscow riot police disrupted the rally on Dec. 21 because it was not authorized and because earlier protests had become disorderly.