The US is taking a go-slow approach on one of the touchiest and least discussed national security issues: whether to remove the last remaining Cold War-era US nuclear weapons in Europe.
Some officials in Germany and other US allies in Europe are advocating a withdrawal, citing President Barack Obama's call last year for a nuclear-free world.
But the US is putting off an early decision, preferring to consult within NATO, starting at a meeting of foreign ministers in April that Secretary of State Hillary Rodham Clinton plans to attend, according to several Obama administration officials.
The officials discussed the matter on condition of anonymity because details are secret and the administration is in the midst of an internal review of the role and purpose of the US nuclear arsenal. The estimated 200 weapons in Europe are a fraction of that total.
Results of the review, originally due to Congress in December, have been delayed repeatedly and now aren't expected before April.
The study, known as the Nuclear Posture Review, is expected to call for a reduced role for nuclear weapons in US national security strategy, as reflected in the substantial reductions being negotiated with Russia in a replacement for the 1991 Strategic Arms Reduction Treaty, or START.
That negotiation does not apply to the US nuclear weapons in Europe, which are categorized as "nonstrategic" because they are short-range bombs designed to be launched by fighter jets based in Europe - including by NATO members' jets.
Ivo Daalder, the US ambassador to NATO, said on Feb 23 that the review "will not make any decisions that preclude any option with respect to nuclear weapons and NATO."
The START negotiations aim to reduce US and Russian long-range nuclear weapons, such as intercontinental ballistic missiles carried on submarines. Talks have bogged down for months.
The White House said Obama on Saturday had an "encouraging" telephone conversation with Russian President Dmitry Medvedev about prospects for an early end to the arms negotiations.
The bombs in Europe are a sensitive subject because they reflect a long-standing US military and political commitment to the defense of its European allies, who have relied on the US nuclear "umbrella" as an alternative to developing their own nuclear weapons.
Washington has a similar commitment to Asian allies, including Japan and South Korea, but it has maintained that role with US-based long-range nuclear weapons.
Asia-based US nuclear arms were withdrawn in the early 1990s by President George H W Bush.
The US government as a matter of policy will not confirm the location of US nuclear weapons, but it is well known that the sites in Europe are in Belgium, the Netherlands, Germany, Italy and Turkey. The US has had nuclear arms in Europe since the 1950s.
Hans M Kristensen, director of the Nuclear Information Project at the Federation of American Scientists, which advocates nuclear arms control, believes the administration is inclined to remove the nuclear weapons from Europe but wants to take a cautious approach.
"The Obama administration came in with a strong pledge to mend ties with the allies, and so the last thing it wants to be seen to do is to make a decision over the heads of the allies," he said in an interview Sunday.
"The US would move these weapons tomorrow if this were just its own decision."
One apparent impediment to an early withdrawal of the weapons is the view of newer members of NATO - those closer to Russia, such as the three Baltic states, which were former Soviet republics.
They see the US weapons as an important symbol of a NATO guarantee of their territorial integrity.
Older NATO members see it differently.
Five of them - Belgium, Germany, the Netherlands, Luxembourg and Norway - in February called for consultations on the question of a US nuclear withdrawal, and NATO Secretary General Anders Fogh Rasmussen said this month that "a hot issue like our nuclear posture" will be on the agenda, beginning at the April foreign ministers meeting.
The consultations are likely to last for months, possibly into 2011.
Parliament members from several European NATO countries are circulating a letter to be sent to Obama stating that the elimination of short-range nuclear weapons in Europe is an urgent matter and should be addressed once the US and Russia complete their START treaty.
"It is the sincere wish of the majority of people in Europe that tactical nuclear weapons are withdrawn from Europe and eliminated," the letter says, according to a copy published by the Global Security Institute, an international group that advocates nuclear disarmament.
The traditional US view of the nuclear bombs in Europe is that they are a pillar of NATO unity and that they link US and NATO security. Even so, they are not targeted at any specific country and the aircraft used to launch them are not as ready for combat as in years past.
An in-depth study of the issue by an expert panel assembled by Defense Secretary Robert Gates, made public one month before Obama took office, said that since 1995 the aircrafts' ability to go into combat with the bombs "is now measured in months rather than minutes."
That study also revealed internal NATO divisions, saying that some senior US officials at NATO's military command headquarters in Mons, Belgium, do not support having US nuclear weapons in Europe.
It quoted one unnamed US general as saying that the weapons are not needed because the American role of deterring a nuclear attack on its allies can be performed with weapons outside Europe.