Moscow ? For the Kremlin and the White House, the signing of the new strategic nuclear arms treaty next month resets, at least for now, a relationship gone badly astray.

Fast friends in the post-Soviet 1990s, Moscow and Washington became increasingly estranged as the U.S. adopted a with-us-or-against-us attitude as the world’s sole surviving superpower. Russia struggled to cope with its loss of superpower status, taking a just-say-nyet approach to diplomacy with the West.

But good will born of the successful arms-reduction effort could revamp the way Washington and Moscow do business — if they can quickly follow up with agreements on other more urgent issues related to nuclear and regional security.

Russia and the U.S. may eventually find they can cooperate more closely in areas where they face common threats, including the Taliban insurgents in Afghanistan and Iran’s nuclear program.

President Barack Obama, accompanied by, from left, Joint Chiefs Chairman Adm. Michael Mullen, Secretary of State Hillary Rodham Clinton and Defense Secretary Robert Gates, makes a statement on the new nuclear arms reduction treaty between the U.S. and Russia. Obama spoke Friday in the press briefing room of the White House.

With increased trust, the two sides also might be able to settle their differences on thorny issues like NATO’s expansion into eastern Europe, plans for U.S. missile defense or the competition for resources in energy-rich Central Asia.

That would mark a significant change.

Russia has been using the remnants of its global power — its seat on the U.N. Security Council, its control of natural gas supplies to Europe and its relationship to rogue regimes — to position itself to frustrate the goals of the U.S., NATO and their allies.

Things got so bad following Russia’s war with tiny U.S.-backed Georgia in 2008 that American leaders rushed to reject suggestions of a new Cold War.

Now, with a new arms treaty expected to slash the U.S. and Russian nuclear arsenals by nearly one-third, a wary Moscow has found a way to say yes.

There are big political benefits for both sides in the arms deal, the successor to the 1991 Strategic Arms Reduction Treaty.

The mere fact that the U.S. spent so much time and effort negotiating an arms pact with Russia has helped bolster Moscow’s claims to being a global force and not just another regional power.

For U.S. President Barack Obama, the treaty helps make good on his promises both to repair American relations with Russia and to work for the goal, some day far in the future, of a world without nuclear weapons.

The immediate effect on global security may be slight, since neither of the world’s nuclear heavyweights is currently threatening the other with Armageddon.

Fyodor Lukyanov, editor of Russia in Global Affairs magazine, called the new treaty “a good sign,” if only because it serves as a symbol that after years of rancor Russia and the U.S. can work together.

Last year the START treaty became the centerpiece of the Obama administration’s initiative to “reset” relations with Russia, which hit rock bottom following the August 2008 Georgia-Russia war.

But the reset proved a lot more complicated than just pushing a big red button, like the one U.S. Secretary of State Hillary Rodham Clinton gave Russian Foreign Minister Sergey Lavrov last March.

Negotiations on the new treaty went slowly, held up initially over Russian objections to U.S. plans for an anti-missile system to protect Europe.

“Probably the most difficult thing of all was to overcome Russia’s deep distrust of the American side,” said Maria Lipman, an analyst with the Carnegie Moscow Center. “That’s because relations had gone so sour under Bush. They reached indeed an all-time low of the post-Communist period.”

The Obama administration, Lipman said, reached its goal through sheer perseverance. “It’s been so many times now upbeat statements, and then yet another statement, yet another hurdle, it looked like the American side was losing patience, especially lately,” she said. “And yet they didn’t lose patience.”