As Russian citizens tearfully leave flowers and condolence notes in front of the American Embassy in Moscow, their acts of solidarity are underlining how a new US-Russian relationship may be forged in the aftermath of Tuesday's terrorist attacks.
Urban terrorism is now a common bond between the two former cold warriors. A string of 1999 apartment block bombings in Russia, which the Kremlin blamed on Chechen separatists, without producing evidence, killed over 300.
Moscow now feels that its repeated warnings of a growing Islamic threat emerging from Central Asia and the Caucasus - and pleas for Western support - are finally being heard in Washington. Some here are suggesting that joint action in crafting a military response may follow.
But a changed dynamic could go either way, analysts warn. The tragedy may help forge a new working relationship, that focuses on sharing intelligence and maybe other assets to fight terrorism. Or President Bush may deepen unilateralist thinking on key strategic issues, shutting Russia and others out of US plans.
The world "must unite in the struggle with terrorism," Russian President Vladimir Putin said during a brief televised address here after the attacks,
"This is the beginning of a new era, in which states are not initiators of war, but targets," says Dmitri Trenin of the Carnegie Endowment for Peace Moscow center. Now "objectively, the US, Israel, and Russia are on the same side." Still, he says, "Many [contentious US-Russia] issues remain on the table."
Defense chief SergeI Ivanov has offered to share any intelligence gathered by Russia that may surface about the culprit. One top suspect, US officials say, is Osama bin Laden, who runs a global network of militant cells from hideouts in Afghanistan.
Any American military strike against targets in the 90 percent of that country controlled by the Islamic Taliban militia, analysts say, must take into account that Russia already has 10,000 troops facing Afghanistan's northern border, in the ex-Soviet republic of Tajikistan.
In August last year, a bin Laden aide seemed to confirm Russian fears, saying that 400 Arab and Afghan fighters had been sent by bin Laden to join separatist guerrillas in Chechnya, a largely Muslim Russian republic.
One card played by Russia - that could be played by the US also, analysts speculate, is providing weapons and adviser support for the anti-Taliban Northern Alliance, led by Ahmed Shah Masood. This option is now complicated by conflicting reports that Mr. Masood may have been killed Sunday.
But issues that have strained recent US-Russia ties, analysts say - from US missile defense proposals, to arms-control treaties and NATO enlargement, to Russian atrocities in Chechnya - still remain. And analysts say the nature of the attack - commercial aircraft being used against American cities, instead of ballistic missiles sent by a "rogue state" - is sure to figure in Russian protests against President Bush's missile-defense shield plans.
"Before [Tuesday], the US believed that a missile defense system was the main guarantee to protect American territory," says Yuri Gladkevich, of the Interfax-Military News Agency. "Now it is obvious that the main threat is not created by, for example, Iranian missile arsenals."
If the focus becomes Afghanistan, room for cooperation is wide, and could focus on Russian technical support for US cruise missile strikes on suspected bin Laden strongholds - the path President Clinton chose, but without Russian help, in 1998 after the two Embassy bombings in Africa.
"Russia is not almighty now, but it is one of the few countries possessing real anti-terrorism experience," Mr. Gladkevich says.
Intelligence services could be brought into the picture also, to share information about militant groups. Just as the CIA played a key role in training mujahideen like Mr. bin Laden, to repel the Soviet occupation of Afghanistan in the 1980s, Baev says, so KGB archives might reveal similar KGB creations like bin Laden who today "might very well be on the same team."
Hurdles to cooperation are high, however, because of cold war baggage. Not even NATO allies share their best intelligence. One reason: Past leaks have partly compromised some NATO operations in Bosnia, Kosovo, and Serbia. "There is a lot of common ground for the intelligence and security communities, but both countries need to stop treating each other as their main adversary," says Mr. Trenin.
"It is important to avoid any simplistic responses" because "there are many bin Ladens," says Vitaly Naumkin, head of Moscow's Center for Strategic and Political studies. Citing "terrorist centers" in Afghanistan, Pakistan, Saudi Arabia, Egypt, and "many places," he says there will be "pressure for some sort of joint military operation ... but I doubt that would be a constructive response.
"Kill bin Laden, and you just make a martyr of him," says Mr. Naumkin. "The root problem lies in the relations between the West and poor countries in an increasingly globalized world."
"My worry is that this act may push Bush toward his instinctive unilateralism," says Baev. "After the first waves of sympathy and vows to cooperate, in the longer term it might make the US go its own way, pushing its own agenda.... It might shape the strategy in a way that Russia may find difficult to deal with."
Fred Weir in Moscow contributed to this report.