Analysts say US concern is not with nurturing democracy but oil and gas
US Vice-President Dick Cheney has said the US wants to work with Azerbaijan on additional routes for exporting the region's oil reserves to the West.
He also pledged support for US allies in the former Soviet Union.
A BBC correspondent says the US sees the states as key allies in protecting access to the region's energy supplies.
Mr Cheney - who will also visit Georgia and Ukraine - spoke as US officials revealed President Bush was to announce a $1bn (Ł0.5bn) aid package to Georgia.
Flanked by Azerbaijan's President Ilham Aliyev, Mr Cheney said: "We've met this evening in the shadow of the recent Russian invasion of Georgia."
He said he was bringing "a clear and simple message for the people of Azerbaijan and the entire region: the United States has a deep and abiding interest in your well-being and security".
But the BBC's Steve Rosenberg, in Moscow, says America's primary concern is not nurturing democracy in the region but rather oil and gas.
Washington wants to benefit from huge energy deposits in the Caspian Sea, but it does not want all the pipelines heading west through Russia.
One Western-sponsored pipeline is already pumping Caspian oil from Azerbaijan through Georgia to Turkey's Mediterranean coast.
There are plans for another pipeline to take natural gas from Azerbaijan and Central Asia and transporting it from Turkey to Austria.
Our correspondent says that, as far as the US and the EU are concerned, the new pipeline is vital if the West is to avoid becoming too energy dependent on Moscow.
Pledge of support
Mr Cheney's trip is likely to infuriate Moscow, which sees Azerbaijan, Ukraine and Georgia as part of its sphere of influence.
In Georgia, Mr Cheney is expected to stress US support for President Mikhail Saakashvili - the man the Kremlin dismissed on Tuesday as a "political corpse" whose leadership it did not recognise.
Russia's President Dmitry Medvedev has also accused the US of helping Tbilisi build its war machine and called on America to review its relations with the Georgian authorities.
"Unfortunately, at a certain point [the US] gave Saakashvili carte blanche for any actions, including military. All that was translated into aggression," Mr Medvedev told Italian television.
Fighting between Russia and Georgia began on 7 August after the Georgian military tried to retake the breakaway region of South Ossetia by force.
Russian forces launched a counter-attack and the conflict ended with the ejection of Georgian troops from South Ossetia and Georgia's other separatist region of Abkhazia.
Russia has since recognised the independence of both regions, though no other country has.