* Negotiations could address tactical, strategic arms
* New treaty talks unlikely soon due to elections
WASHINGTON, Feb 10 (Reuters) - The next round of U.S.-Russian nuclear arms talks is likely to focus on the delicate task of reducing a much broader range of atomic weapons, U.S. negotiators said on Friday as they discussed the first anniversary of the New START treaty.
Ted Warner, senior adviser to the undersecretary of defense for arms control, said the United States and Russia had reached a point where negotiations needed to include strategic and tactical weapons, regardless of whether they are in storage or mounted on delivery vehicles.
New START, which went into force in February last year, commits the two sides to reducing their strategic, or longer-range, deployed nuclear weapons to 1,550 per side, down from the previous ceiling of 2,200.
The treaty did not address tactical, or shorter-range, nuclear weapons, or even stockpiles of strategic warheads held at storage facilities apart from their delivery vehicles.
The United States said in 2010 that its total nuclear stockpile, including deployed and non-deployed, tactical and strategic nuclear weapons was 5,113.
Russia has not made public its total arsenal, but is believe to have a stockpile "in shouting distance of that," Warner told a forum at the Brookings Institution think tank in Washington.
Warner said President Barack Obama made it clear when he signed New START that he hoped to move ahead with another round of nuclear arms talks that would look at the full range of atomic weapons.
"What the president said is ... the next time we look at this, we really ought to look at the total operational inventory, the nuclear stockpile of operational weapons," he said. "And that would be strategic and nonstrategic, and both deployed and non-deployed."
Rose Gottemoeller, assistant secretary of State for arms control, said work on New START over the past year had helped lay the groundwork for a new round of arms control talks but "the next treaty will be one that I think takes us in some more challenging directions."
A treaty dealing with non-deployed weapons would require opening sensitive storage facilities to inspection and verification, she said.
A treaty incorporating tactical nuclear arms would require greater openness and transparency about conventional systems like missile defense or U.S. plans for "Prompt Global Strike," a conventional weapon that could hit any target on Earth in about an hour.
With Russia and the United States in the process of holding presidential elections, neither side is in a position to move ahead with a new round of nuclear arms talks right away.
For now, the sides are carrying out what Warner described as "homework" as they attempt to set the stage for a renewal of arms control discussions once elections are over.
The United States is conducting a Nuclear Posture Review implementation study, which will allow Obama to issue guidance to the Pentagon about the future size and scope of the country's nuclear arsenal.
The implementation study informed the Pentagon's strategic review issued in early January, which said the administration believes it can maintain an effective nuclear deterrent with fewer warheads.
NATO is conducting a similar review looking at the nuclear, conventional and missile defense forces it believes will be needed to protect the Western alliance over the next decade.
The aim is to have NATO leaders formally approve the Deterrence and Defense Posture Review at their summit in Chicago in May.
Meanwhile, U.S. and Russian negotiators are holding regular Strategic Stability Talks this year on a range of issues in an effort to lay the groundwork for new arms control talks.
"The Russians have made clear if we're going to move on to further nuclear reductions, there are a set of issues that need to be addressed at least in parallel as this goes along," Warner said.
Those issues include the Prompt Global Strike weapon and the European missile defense system being assembled by the United States and its NATO allies. Russia views both as a threat to its nuclear deterrent. (Reporting By David Alexander; Editing by Xavier Briand)