WASHINGTON, May 14 (Reuters) - An influential Bush administration adviser said on Tuesday Russia should be forgiven its Soviet-era debt as a way of persuading Moscow to end troubling nuclear cooperation with Iran.
With an agreement on slashing strategic nuclear weapons now secured, Iran looms as a key remaining irritant ahead of a summit in Moscow on May 23 between President George W. Bush and President Vladimir Putin that will underscore a new era in U.S.-Russian relations.
Richard Perle, chairman of the Defense Policy Board that advises the Pentagon's civilian leadership, said Washington should find a way to "share the burden" if Moscow restrains trade with Tehran, with a serious impact on the Russian economy.
"Our problems with Russia now have to do largely with Russian relations to third countries, and they are rather heavily focused on the confluence of business and commercial interests and security concerns that flow from that," he said.
"Those issues can and should be ironed out, and in doing so I think we need to pay attention to Russia's economic situation," Perle said.
"We should cancel the Soviet-era debt (because) there is no reason why people struggling to create a free society should be burdened by the debts of a totalitarian society," he added.
Perle spoke at a Council on Foreign Relations program that looked at prospects for the Moscow summit.
Bush has branded Iran part of the "axis of evil" with North Korea and Iraq because of its weapons of mass destruction programs. One of the last unsettled financial questions of the Cold War is Russia's $42 billion Soviet-era debt to private Western lenders.
The United States repeatedly has urged Russia to end what Washington says is cooperation with Iran's nuclear, ballistic missile, biological and chemical weapons programs.
But the pressure has had little effect. Despite improvements in Russia's economy, U.S. intelligence says the troubling ties with Iran have continued because Russia's state-run defense, biotechnology and nuclear industries remain strapped for funds.
Russian officials, while acknowledging a role in developing a civilian nuclear reactor for Iran at Bushehr, have denied they are aiding Tehran's nuclear weapons program.
In an effort to persuade Moscow otherwise, the United States provided Russia with evidence of its allegations. After that, Perle said, the sources providing Washington with intelligence on Russia stopped doing so.
The Iran issue is expected to be raised at the Moscow summit, but U.S. officials have said they do not expect an immediate resolution.
Bush and Putin will sign, however, a treaty slashing U.S. and Russian nuclear arsenals from 3,000-3,500 warheads to 1,700-2,200 warheads each by the end of 2012.