The United States is not "particularly concerned" that the talks on strategic arms reductions with Russia are taking a longer time than previously expected, the State Department said Tuesday.

Moscow and Washington are expected to sign a new document to replace the Strategic Arms Reduction Treaty (START 1) treaty, which expired on December 5, at the beginning of 2010.

"The 5th [of December] was a point at which the existing treaty expired by agreement between the two countries. We are abiding by the spirit of that agreement as we continue these negotiations," Assistant Secretary of State Philip J. Crowley told a daily press briefing.

"We had hoped to resolve the complex issues that these treaty negotiations present by the end of the year. I don''t think that we''re particularly concerned, given the complexity of these issues, that it''s taking a longer period of time," he said.

"The U.S. delegation led by Assistant Secretary Rose Gottemoeller has returned for a recess from the START negotiations in Geneva. The team has gone through an intensive period of negotiations with their Russian counterparts over more than two months," Crowley said.

He added that the U.S. expects the teams to "resume their negotiations in Geneva in mid-January."