* Obama, Medvedev sign nuclear treaty in Prague
* Both say new sanctions may be necessary on Iran
* Putin first to recognise interim Kyrgyz government
* Obama seeks Russian backing for Iran sanctions
(updates with statements by leaders)
By Jan Lopatka and Caren Bohan
PRAGUE, April 8 (Reuters) - The United States and Russia
signed a landmark strategic nuclear disarmament treaty on
Thursday and said new sanctions may be necessary to put pressure
on Iran to renounce its nuclear ambitions.
Presidents Barack Obama and Dmitry Medvedev signed the pact
at a ceremony in the mediaeval Prague Castle after talks that
covered nuclear security, Iran's atomic programme and an
uprising in the Central Asian state of Kyrgyzstan, where both
major powers have military bases.
The treaty will cut strategic nuclear arsenals deployed by
the former Cold War foes by 30 percent within seven years, but
leave each with enough to destroy the other.
Obama said the agreement had "ended the drift" in relations
between Moscow and Washington and sent a strong signal that the
two powers that together possess 90 percent of all atomic
weapons were taking their disarmament obligations seriously.
"We are working together at the United Nations Security
Council to pass strong sanctions on Iran and we will not
tolerate actions that flout the NPT," he said, referring to the
Nuclear Non-Proliferation Treaty.
"My expectation is that we are going to be able to secure
strong, tough sanctions on Iran this Spring," he added.
Medvedev said he regretted Tehran had not reacted to
constructive proposals on its nuclear programme and the Security
Council might have to take further sanctions, but they should be
"smart" and not bring disaster on the Iranian people.
"Today we had a very open, frank and straightfoward
discussion of what can be done and cannot be done," the Russian
president said, adding he gave Obama a list of Moscow's limits.
Russian Deputy Foreign Minister Sergei Ryabkov declined to
detail the list but told reporters a total embargo on deliveries
of refined oil products to Iran, for example, would be
unacceptable since it would cause a "huge shock for the whole
society and the whole population".
The situation in Kyrgyzstan, where opposition protesters
forced out President Kurmanbek Bakiyev on Wednesday, thrust its
way on to the agenda as both Washington and Moscow have military
bases in the poor Central Asian state. The U.S. base at Manas is
vital for supplying NATO forces in Afghanistan.
Russian Prime Minister Vladimir Putin effectively recognised
the interim Kyrgyz government formed by opposition leader Roza
Otunbayeva on Thursday, speaking to her by telephone, his
spokesman said. The State Department declined immediate comment
on whether Washington would follow suit.
U.S. SHIFTS DOCTRINE
Obama this week announced a shift in U.S. nuclear doctrine,
pledging never to use atomic weapons against non-nuclear states,
as he sought to build momentum for an April 12-13 nuclear
security summit in Washington.
The U.S. president reaffirmed the long-term goal he set in a
speech at the same Prague Castle a year ago to work towards a
world without nuclear weapons and said Medvedev would visit the
United States later this year to discuss further cooperation,
including withdrawing short-range tactical nuclear weapons.
Both men said they hoped and expected the new treaty would
be ratified this year. Medvedev, mindful of past problems in
winning approval in the treaty-shy U.S. Senate, said the
ratification process should "proceed simultaneously". Obama said
he was convinced there would be bipartisan Senate support.
Medvedev reaffirmed Moscow's warning that it could withdraw
from the treaty if U.S. missile defence plans undermined the
basis for strategic arms control.
Analysts said the signing would help Obama build pressure on
Tehran, along with the 47-nation nuclear summit in Washington
and a meeting with Chinese President Hu Jintao next week.
Steven Pifer, an arms control expert at the Brookings
Institution, said the pact with Russia would give the U.S.
delegation more credibility at the non-proliferation conference.
"If the United States and Russia were to show up with no
agreement and between the two of them controlling 95 percent of
the weapons, it's pretty easy for the non-nuclear states to say,
'well you're not doing your part, why should we?'," Pifer said.
Obama's new nuclear strategy document broke with former
President George W. Bush's threat of nuclear retaliation in the
event of a biological or chemical attack.
The assurance applies only to countries in compliance with
the nuclear Non-Proliferation Treaty, so Iran and North Korea
would not receive that commitment.
Washington and Moscow have plenty of differences on issues
ranging from Iran to missile defence, but the two leaders strove
to highlight common ground, including on economic cooperation.
However, they did not mention Russia's stalled bid to join the
World Trade Organisation.
Obama has put a priority on trying to "reset" relations with
Moscow that hit a post-Cold War low during Russia's 2008 war
with Georgia, and the treaty could help that.
The successor to the 1991 Strategic Arms Reduction Treaty
would limit operationally deployed nuclear warheads to 1,550,
down nearly two-thirds from START I.
Later on Thursday, Obama will dine with 11 heads of state
from central and eastern Europe. Czech diplomats said the
meeting was designed to reassure former Soviet bloc countries
that resetting relations with Russia would not diminish U.S.
interests in the region.
(Additional reporting by Jana Mlcochova and Denis Dyomkin in
Prague and Jon Boyle in London; writing by Paul Taylor; editing
by Matthew Jones)
