“At the moment we are engaged in what I would say is a ‘homework period,’” said Rose Gottemoeller, Assistant Secretary of State for the bureau of arms control, verification and compliance. “We are preparing a way for new negotiations but we are not yet ready to embark on new negotiations.”

When President Barack Obama signed the new Strategic Arms Reduction Treaty (START) with Russia on April 8, 2010 he pledged to look forward to future nuclear arms negotiations and began planning for them, Gottemoeller said.

Obama sought a deal on new categories of arms in future reduction negotiations, she said.

“The first category would be further reductions in deployed nuclear warheads. These warheads are the easiest ones to see from outer space, from either Russian satellites or U.S. satellites. Up to this point in the history of arms control efforts we've always focused on deployed weapons,” she said.

The U.S. also wanted a deal on other nuclear weapons.

“One - non-deployed nuclear weapons, weapons that are in storage facilities or reserve, and the third category is non-strategic weapons or tactical nuclear weapons. Those last two categories are brand new and for that reason we have been very interested in working with the Russian Federation on some new approaches that will be necessary for verifying such agreements,” Gottemoeller said.

The United States is also interested in some of the conceptual and definition questions that are involved, because “what we consider a tactical nuclear weapon may be different from what the Russian Federation considers to be a tactical nuclear weapon or non-strategic nuclear weapon,” she said.