SINGAPORE - The Russian and U.S. presidents said on Sunday they hoped to strike a new deal for arms cuts by the end of the year.

After talks in Singapore as part of efforts to reset relations between the two countries, officials on both sides acknowledged unresolved problems in the talks on a new arms pact to replace START I, which expires in December.

I hope that, as we agreed earlier ... we can finalize the treaty by December, Russian President Dmitry Medvedev said after talks with U.S. President Barack Obama in Singapore.

The two leaders view the new treaty as an important element of maintaining global strategic stability and healing relations which sank to post-Cold War lows during the presidency of Obama's predecessor, George W. Bush.

Officials expressed optimism that a new document could be ready by the time or soon after the START I (Strategic Arms Limitation Talks) arms cuts pact expires on December 5.

On the new START Treaty, we progressed, Michael McFaul, senior White House adviser said after Sunday's meeting.

We talked about some sticking issues that still have to be resolved and both presidents committed to trying to get a new treaty in place by the end of the year.

They said that publicly and that was a big part of the discussions on the substance of that treaty, he told reporters.

Officials on both sides said Obama and Medvedev also discussed Iran's nuclear program and Afghanistan during their 90-minute talks on the sidelines of a regional summit.

Each meeting with the U.S. president gives a new substantial impetus to bilateral ties, Sergei Prikhodko, Medvedev's chief foreign policy adviser, told reporters ahead of the meeting.

BIGGEST IRRITANT

Earlier this year, Obama removed the biggest irritant in bilateral ties by scrapping plans to deploy interceptor missiles in Poland and a radar in the Czech Republic, parts of a projected U.S. anti-missile defense against a strike by Iran.

Russia insists that anti-missile defense and strategic arms cuts pacts are closely interlinked.

However, before the Obama-Medvedev meeting the Russian media reported major unresolved problems concerning the new arms cuts pact. Kommersant daily said Moscow and Washington had no agreement on ceilings for the number of nuclear warheads and on whether the pact should handle Russian mobile missile complexes.

Prikhodko did not comment on the differences and on whether they could be overcome by December 5. He said the leaders viewed the quality of the new pact rather than the timing as a priority.

We are satisfied at the moment by the quality of open and pragmatic dialogue with the U.S. administration, he said.

It allows us to hope for fruitful work on problems, where a solution has not been found yet.

(Editing by Michael Roddy)

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