“IT’S TIME, people of China! It’s time. The square belongs to everyone.” Thus begins the poem we reprinted on the opposite page last week by Zhu Yufu, a veteran Chinese democracy advocate. On Friday, just four days before China’s next top leader is due to meet President Obama at the White House, Mr. Zhu was sentenced to seven years in prison for “inciting subversion.”

Beijing used to lay the groundwork for important U.S.-China meetings by releasing dissidents. Now it does the opposite. In the past seven weeks four pro-democracy activists have been handed lengthy jail sentences, and a fifth has been driven into exile. Chinese security forces meanwhile are conducting an offensive in Tibet and nearby areas, where at least six peaceful protesters have reportedly been shot in recent weeks.

Mr. Zhu’s sentencing was probably not a deliberate provocation to the United States before the Washington debut of Xi Jinping. Instead the Chinese leadership appears to be preoccupied with eliminating any possibility of a popular “Jasmine revolution” during a year in which Mr. Xi is due to succeed Hu Jintao as Communist Party general secretary.

Nevertheless, Mr. Xi and his comrades clearly have calculated that locking away peaceful opponents will have no impact on the new leader’s reception at the White House, State Department and Pentagon — all of which he is due to visit. Mr. Obama has encouraged this conclusion by failing to speak up about Chinese repression at past summits. After meeting Mr. Hu in Washington a year ago, Mr. Obama appeared to excuse Beijing’s repression and affirmed that it “doesn’t prevent us from cooperating in other critical areas.”

The president has an opportunity to shift that misguided approach as he begins a relationship with Mr. Xi. During Mr. Hu’s decade-long tenure China has become steadily less free politically. While a popular revolution may not be imminent, that trend is not sustainable in a country with a rapidly growing middle class and a growing appetite for free expression on the Internet. Meaningful political reform will be essential if Mr. Xi is to keep China on a stable course during his tenure. That means it is also an important interest of the United States, one that ought to be at the center, not the margin, of the bilateral relationship.

At a briefing in Beijing for journalists ahead of Mr. Xi’s trip, Chinese Vice Foreign Minister Cui Tiankai complained that “a trust deficit” was holding up “the further expansion of our bilateral relationship.” That means the leadership expects Mr. Obama to do something to appease Mr. Xi, such as curtailing plans for an expanded U.S. military presence in East Asia. What the president ought to do instead is explain to the new leader why, for the United States, China is untrustworthy: because it continues to imprison courageous people like Zhu Yufu.