Credible diplomacy is all about sending consistent signals, especially for a U.S. president.

In that respect, the signing of a new nuclear arms pact last week was a big win for Barack Obama and U.S.-Russian relations, particularly as world events seemed to conspire to push the two former antagonists closer together.

Effective diplomacy is also about earning consistent and supportive signals in return, not the sort of face slaps tried on the U.S. recently by Israel's Benjamin Netanyahu and Afghanistan's Hamid Karzai.

Obama put them both down promptly. His presidential voice carries more weight than just a few weeks ago.

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U.S. President Barack Obama and his Russian counterpart, Dmitry Medvedev, display their signatures on the new Strategic Arms Reduction Treaty (START II) at Prague Castle on April 8, 2010. (Reuters)

It's an odd political world where the difference of a few congressional votes on a subject such as health care can be said to define a presidency's success.

But Obama's influence abroad is clearly greater if he is seen to be a winner at home.

And as this influence is now being directed at dramatically curtailing the world's nuclear arsenal, we may all be the beneficiaries.

The Russia deal

In the space of a very short time, Obama capped his domestic legislative success with a (SALT II) nuclear arms treaty with Russia that cuts warheads and launchers, and creates a fairly extensive mutual inspections regime.

Among other things, the signing shows Obama actually means it about nuclear build-down and that the re-set button has been pushed with the Kremlin.

The hope now is that, with Russian support, the UN Security Council will be more apt to approve sanctions against Iran over its apparent nuclear ambitions.

Obama, it is worth noting, is the first U.S. president to make nuclear disarmament a central foreign policy theme. 

He seems genuinely convinced that any proliferation of nuclear weapons would be the greatest threat to world security in the foreseeable future.

That is why, this week, he is hosting a nuclear summit of about 40 key countries — though not Iran, not North Korea, and, at this point, not Israel, all reluctant to get into a global discussion of what they do or don't or ought to have in the way of nuclear weapons.

In the run-up to this summit, Obama also announced a new U.S. nuclear defence posture, which commits Washington never to employ nuclear weapons against a non-nuclear state that had signed the non-proliferation treaty — unless that state was not in compliance with its obligations, a caveat that also sends a cautionary signal Iran's way.

Choosing his guy

As for Russia, Obama's pre-summit nuclear deal with Moscow is sending the signal that he has "stopped the drift" in relations between the two countries. A subtler message is that his partner of preference is President Dmitry Medvedev.

Most Western commentators claim Medvedev is just Vladimir Putin's poodle. The truth is much more complicated.

Astute Moscow observers see them not as master-slave, nor as rivals, but as a harmonious duo in basic agreement on the issues but with different emphases and styles — and also different constituencies.

Putin's patriotic brashness appeals to older, more conservative and usually rural Russians. While Medvedev's message of modernization and reform earns support among the upwardly mobile.

At the moment, the fact is that Medvedev's constituency is growing, while Putin's shelf life may be approaching. That being said, Putin is still seen as a political carnivore to Medvedev, a political vegan.

Betting on the Kremlin

After the Moscow subway bombings, it was important that Medvedev came across also as a credible tough guy, which success on the world stage — being seen as Obama's equal — can only help.

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What the Washington nuclear summit is all about: A long-range, Sejil 2 missile is test-fired somewhere in the Iranian desert in December 2009, according to this handout photo from the Iranian military. (Reuters)

Russia is less interested than Obama in world nuclear disarmament and in sanctioning Iran. Its main aim is to regain its former role as a negotiating equal with the U.S.

Over the past 15 years or so, the signals from Washington have been that Moscow didn't count for much anymore, which seriously contributed to the Kremlin's sullenness in recent years.

At the same time, this new rapprochement worries those European countries whose publics still resent their decades under the Soviet boot.

That is why Obama chose to sign this new treaty in Prague, arguably the most shameful locale of Soviet Cold War diktat, to try to signal that it is time to turn the page.

He invited the leaders of the 11 EU states from Central and Eastern Europe to a Prague dinner to try to calm their concerns.

Now, he has to hope the Russian leadership won't let him down.

Krygyzstan

One test of this new relationship will be the unlikely locale of Kyrgyzstan, where America's image has taken a beating, and not just among local democrats.

A picturesque but poor state up against the Himalayas, Kyrgyzstan was the only one of the five Central Asian republics to emerge from the break-up of the Soviet Union with any real inclination for democracy.

Since then, however, the country has undergone two revolutions, the most recent just last week, to turf out initially well-intentioned leaders who inevitably fell prey to the temptations of power.

One of the hard truths about democratic transition is that it takes time and considerable restraint from well-meaning outsiders not to pick winners, but to support the long passage to the rule of law and a healthy civil society. It's a steep climb for folks who have not actually been there before.

But because of the overwhelming strategic importance of Krygyzstan to the Afghan war effort, Obama had to cut a deal with the now deposed Krygyz strongman Kurmanbek Bakiyev, to keep the lease to the Manas air base, the only staging and supply point from outside Afghanistan for the U.S. military.

Russia had actually offered Bakiyev $2 billion to end the U.S. lease of Manas. Obama had to offer the dictator a better, sweetheart deal to stay, adding an admiring personal letter to seal it.

That U.S. signal was deeply resented by the Kyrgyz democratic opposition, possibly egged on by the Russians.

Now, if he wants to keep control of that staging ground, Obama is probably going to have to take account more of Russia's views on neighbouring Afghanistan and move decisively to support democracy in Kyrgyzstan.

In the end, that is what effective American diplomacy is all about anyway.

Until now, Obama has been less than stalwart in his support for human rights and democracy abroad, and dictators everywhere, including Kyrgyzstan, have noticed. 

A country such as Russia may dream of days gone by, when the superpowers were only two. Today, though China has risen, there is still only one — Washington.

But U.S. power resides mostly in the unflinching American commitment to universal aspirations and values  — like ridding the world of nuclear weapons and consistently supporting human rights.

That is what the Obama era ought to be all about.