The U.S. has also been furthering economic ties with Georgia in the middle of fresh invasion threats from Moscow.

By increasing its presence, the United States has worried other regional powers, namely Russia and Iran. Moscow fears that the United States will gain more control over the oil and gas deposits in the southern Caucasus, in countries such as Georgia and Azerbaijan.

Tehran fears that increased U.S. involvement around Iran may limit their country's economic growth and possibly even threaten its existence.

Iran recently built a gas pipeline from Turkmenistan and is currently planning a new pipeline with India; Tehran also fears that increased U.S. influence in oil-rich Azerbaijan could limit Iran's access to oil drilling sites in the Caspian Sea. How the resources of the Caspian will be divided is still under contest with the five bordering countries -- Iran, Azerbaijan, Russia, Kazakhstan, and Turkmenistan -- vying for rights. Further, U.S. corporations are planning on building oil and gas pipelines out of the oil and gas rich Caucasus and Turkmenistan bypassing Iran.

Along with encroaching U.S. troops on its eastern border with Afghanistan, many in Tehran worry about possible U.S. troops along its western border with Iraq. Iran and Iraq have strengthened economic cooperation recently with the Iraqi-Iranian joint committee for trade and economic cooperation. Both sides stressed the development of bilateral cooperation in all fields. All of this may be squandered any day with a U.S. invasion of Iraq. While many in Iran would not mind seeing Hussein go, the prospects of having the U.S. military next door is not a desirable alternative.