WASHINGTON (AP) - President Barack Obama, after meeting with a top Russian official on Thursday, said he thinks the United States and Russia can narrow their differences over nuclear weapons, the Middle East and several other issues.

Obama met at the White House with Russian Foreign Minister Sergey Lavrov. They discussed a number of issues likely to come up when Obama visits Moscow in July.

"We have an excellent opportunity to reset the relationship between the United States and Russia on a whole host of issues," Obama told reporters after the meeting. Those issues, he said, include nuclear proliferation, the situations in Afghanistan and Pakistan, conflicts in Iraq and the Middle East, and the worldwide economy.

Lavrov, who met earlier with Secretary of State Hillary Rodham Clinton, said, "I think we work in a very pragmatic, businesslike way" to resolve differences between the two countries.

Clinton and Lavrov said earlier that recent differences over Georgia will not stand in the way of arms control negotiations.

In a cordial appearance during Lavrov's first visit to Washington during the Obama administration, the officials expressed optimism that their countries were easing disagreements that have roiled relations in recent years.

Lavrov said through an interpreter that reducing nuclear arsenals was "too important both for Russia and the United States and the rest of the world to hold hostage."

However, the meeting came as tensions flared over NATO exercises in Georgia. Ahead of his arrival in Washington, Lavrov canceled a May 19 meeting at NATO to protest the exercises.

On Wednesday, Russia announced the expulsion of two Moscow-based NATO officials in a tit-for-tat move after NATO revoked the accreditation of two Russian envoys to alliance headquarters in Brussels.

NATO did not give a reason for the April 30 revocations, but Russia suggested the move was tied to a February espionage scandal in which Moscow was accused of accepting NATO secrets from a spy.

Other disagreements that emerged under the Bush administration also remain. Washington and Moscow appear divided on how to rein in Iran's nuclear ambitions, for instance.

On Thursday, with Clinton, Lavrov repeated Russia's opposition to EU and U.S. sanctions against Iran, insisting that actions should be coordinated within the United Nations' Security Council.

And while the United States has put its contentious missile defense plans in Europe under review, that disagreement has not been resolved.

Lavrov said the two sides continue to discuss Russian proposals for cooperation and compromise on missile defense.

The Obama administration wants to emphasize topics the two sides might agree on: new arms control and nonproliferation talks.

"It is, I think, old thinking to say that we have a disagreement in one area, therefore we shouldn't work on something else that is of overwhelming importance," Clinton said. "That's just not how we think."

U.S. and Russian negotiators have recently begun negotiating to replace the 1991 Strategic Arms Reduction Treaty, or START, which expires at year's end. Those talks were launched after the first face-to-face meeting between Obama and Russian President Dmitry Medvedev last month.

The two leaders appeared to set a new tone in relations, promising cooperation on a host of issues. The Obama administration's attempt to engage Moscow marks a break from the Bush administration, which didn't like extensive arms control negotiations and angered Moscow with its intention to install a missile defense system in Poland and the Czech Republic.