Clinton's agenda for Russia trip reflects improving but fragile relationship

Negotiations on the new nuclear-arms treaty illustrate the continued wariness in the relationship. In July, during a summit with Medvedev, President Obama declared that an agreement "will be completed this year" to replace the expiring START.

But the talks have dragged on, with "a thousand catches" emerging in recent weeks, according to a senior Pentagon official, James Miller, who testified before Congress on Tuesday.

Some U.S. analysts accuse the Russians of bringing up last-minute objections as a negotiating tactic. The Russians note that they were ready to start renegotiating the treaty years before it expired but that the Bush administration was in no hurry.

A latest complication in the talks is a flap over missile defense. Russian authorities have long worried that the United States could get the upper hand as a nuclear power because of its more advanced missile-shield programs. The Kremlin was relieved last year when Obama scrapped Bush's plan for a long-range missile defense system based in Europe, substituting a design featuring shorter-range missiles.

But when Romania recently announced that it would host elements of the new missile shield, the Russians cried foul. The Obama administration had largely persuaded the Russian side to leave the issue out of the START talks, but suddenly it was back on the table, officials said.

Fyodor Lukyanov, editor of the journal Russia in Global Affairs, said the clash was over trust, rather than the fundamentals of the missile defense system.

"The way the Obama administration disclosed it, without advance notice to the Russian Federation, that unfortunately contributes to mistrust. . . . Psychologically, it was an unhappy move," he said.

A U.S. official familiar with the matter said the Russian government had been briefed for months about the new system but was not told which countries would host the components. He said the U.S. government was not going to "ask permission" from Russia on where to install it. But he acknowledged that the two sides could have done a better job of consulting.

Analysts say dealing with Russia is particularly fraught because its political and military elites are divided over how close the country should get to the United States.

"I think they are still in the sort of show-me posture. They're waiting, or believe the returns are still out on how serious the United States is about this," said James F. Collins, a former U.S. ambassador to Moscow who is now at the Carnegie Endowment for International Peace.