MOSCOW -- When President Barack Obama flies into Moscow today for meetings with Kremlin leadership, at the top of his agenda will be reducing the number of strategic nuclear weapons capable of destroying life on Earth. And that might be the easy part.

Mr. Obama's trip to Russia is viewed on both sides of the Atlantic as a chance to resuscitate relations between the two nations after they fell to post-Cold War lows during the presidency of George W. Bush.

In order to do so, Mr. Obama and Russian President Dmitry Medvedev appear to be taking a more pragmatic tack than did their predecessors: concentrating first on the issues called "deliverables" in the parlance of the diplomatic community, or things that can get done, instead of getting stuck on thornier issues.

There is measured hope that a combination of the financial crisis -- which humbled Russian rhetoric after both a credit crunch and lower commodity prices hit hard here -- and signals from Mr. Medvedev, however conflicted, that he's willing to pursue political reform, has created an opening for Mr. Obama to "reset" diplomatic ties.

Progress is anticipated on arms control -- expected to be a centerpiece of the agenda -- as well as on trade, counter-narcotics and support for transporting Western military supplies to the Afghan theater.

It's a delicate task in an uncertain setting. To begin with, there is a question of whether Mr. Obama is dealing with the real leader of the country. The prime minister and former president, Vladimir Putin, is widely regarded as the ruler of Russia and the driving force behind a revival of nationalism and authoritarian rule that has been funded by oil and gas money.

During the past year, Mr. Putin was the most visible and bellicose representative of the Russian invasion of U.S. ally Georgia, and then the dispute that led to a cut-off of Russian gas to U.S. ally Ukraine and much of Europe.

However, because of diplomatic protocol, Mr. Obama will spend more time with Mr. Medvedev, a friendlier face, than with the prime minister.

American officials have said they are aware of the complexities of Russia's "ruling tandem." Critics of the Kremlin warn that Mr. Putin's deep distrust of the West could short-circuit attempts for substantial change.

In an interview with the Associated Press on Thursday, Mr. Obama acknowledged the dilemma. "I think that it's important that even as we move forward with President Medvedev, that Putin understands that the old Cold War approaches to U.S.-Russian relations is outdated, that it's time to move forward in a different direction," Mr. Obama said.

"The problem is that Putin has based his campaign on anti-American rhetoric," said Boris Nemtsov, a deputy prime minister in the late 1990s and one of the few national political opposition leaders still in Russia. "Obama believes that democracy is a universal value; Putin believes that it is a universal threat."

Mr. Obama and Mr. Medvedev have pledged to extend or replace the Strategic Arms Reduction Treaty (START) -- a 1991 agreement to reduce the number of long-range nuclear warheads in both countries, which is set to expire in December.

After their April meeting in London, the two leaders set an apparent benchmark by saying they would go below the levels set by a 2002 pact, known as the Moscow Treaty, which calls for no more than between 1,700 to 2,200 strategic warheads in each country by the end of 2012.

As with much of U.S.-Russia relations, the matter still faces a stumbling block.

The Kremlin is angry about a planned U.S. missile shield in Eastern Europe that was pushed by the Bush administration.

Russian leaders say they fear that the system, which would be based in Poland and the Czech Republic, is not aimed at stopping an Iranian attack, as Washington insists, but rather at weakening Russia's nuclear deterrent -- the cornerstone of its military power.

Mr. Medvedev greeted Mr. Obama's victory at the polls last November by threatening to deploy missiles in Kaliningrad, near Poland, "to neutralize, if necessary, the anti-ballistic missile system in Europe." The timing was inept, and has led some to wonder whether the speech was prepared for a win of the presidency by Arizona Sen. John McCain, the Republican candidate.

Mr. Obama has said the shield is under review, amid questions about its funding and whether it would actually work.

One way around the standoff would be to link Russia to a broader anti-missile system, an offer Washington raised but that Moscow so far has shunned.

The disagreement about the shield taps into the broader problem Russian officials and analysts say is at the core of troubles with the United States. This is the question of Russia's contested influence over the so-called "near abroad" countries. Russia's war with Georgia last August, for example, resulted in the de facto annexing of two regions in that country.

While the Obama administration has signaled it's not going to press NATO as aggressively as Mr. Bush did to admit Georgia and Ukraine, it's clear that those fault lines remain in place.

During a teleconference last week, a U.S. official dealing with Russian affairs said that Mr. Obama is looking for ways to work with the Kremlin, but would not be willing to swap U.S. interests for Russian cooperation.

"We are not in any way, in the name of the reset, abandoning our very close relationships with these two democracies, Ukraine and Georgia," said Michael McFaul, senior director for Russian and Eurasian Affairs at the National Security Council.

For the Kremlin, there is little compromise on being able to project power in what is referred to here as a "privileged sphere."

From the Russian viewpoint it's an existential matter, said Vyacheslav Nikonov, head of Politika, a pro-Kremlin think tank.

Obama officials say the president will spend much of his second day in Moscow speaking with civil society leaders, and giving what's billed as a major speech that is expected to at least touch on the question of open governance, a clear indication democracy is still on the agenda.

Before those meetings tomorrow, though, Mr. Obama will have breakfast with a powerful Russian politician: Vladimir Putin.