ANKARA

With Iran surrounded by dozens of U.S. military bases and nearly 65,000 American troops, uncertainty prevails on whether Washington's killing of a top Iranian general will provoke an all-out war between the two nations.

The death of Iran's Islamic Revolutionary Guards Corps (IRGC) Quds Force commander, Major General Qasem Soleimani, at the hand of a U.S. drone strike marked a dramatic escalation in tensions between the U.S. and Iran -- which have long been at a fever pitch since U.S. President Donald Trump chose in 2018 to unilaterally withdraw Washington from a 2015 nuclear pact between world powers and Tehran.

Since Iranian Supreme Leader Ali Khamenei vowed "severe retaliation" after the killing, the IRGC launched at least a dozen ballistic missiles early Wednesday against U.S.-led coalition forces in neighboring Iraq.

At least two Iraqi military bases hosting U.S. military and coalition personnel at Ain al-Assad and Erbil were targeted, Pentagon spokesman Jonathan Hoffman said in a statement.

Later, Iranian Foreign Minister Javad Zarif said Tehran "concluded" proportionate measures in response to the killing of Soleimani last week, adding that Tehran was not looking for a war with the U.S.

American and Iraqi sources have yet to report any casualties.

Trump, for his part, said he would be making a statement on Wednesday after the Iranian strike, adding that "all is well" regarding preliminary assessments of the incident.

Amid escalating tensions, the U.S. deployed additional troops to the region despite Trump's earlier attempts to withdraw personnel, as well as a letter supposedly sent by the Pentagon to Baghdad suggesting plans to leave Iraq.

Trump had called this "unsigned" letter a "hoax".

Afghanistan

Since invading Afghanistan weeks after the 9/11 attacks on the World Trade Center in New York, Washington's "War on Terror" has prevailed and enabled U.S. presence in the Middle East and southern Asia.

Eighteen years of war with the Taliban insurgency have yielded no lasting success, with the Trump administration engaging in successive rounds of diplomacy with Taliban representatives in the Qatari capital of Doha.

The U.S. aims to reduce its nearly 14,000-troop presence in Afghanistan by more than half, leaving around 6,000 behind if a truce can be achieved between the Taliban and Kabul.

There are six known U.S. military bases in Afghanistan, the Bagram Airfield near the capital Kabul being the largest. Many of these bases are close to the Iranian border.

Qatar

The Gulf nation of Qatar hosts the U.S.'s largest military base in the Middle East. Al Udeid Air Base, which was built after the first Gulf War, is home to an estimated 13,000 troops and is the headquarters of the U.S. Air Force Central Command (CENTCOM).

Boycotted and threatened since 2017 by other major Gulf nations, especially Saudi Arabia, Bahrain and the U.A.E., Qatar enjoys warm relations with Turkey and Iran.

The U.S. has recently positioned B-52 bomber airplanes able to carry nuclear weapons at the base since relations with Iran began to deteriorate.

Bahrain

Washington has had a military presence in the Kingdom of Bahrain since World War II.

The Naval Support Activity Bahrain base operates as the headquarters for both the U.S. Navy's Fifth Fleet and U.S. Naval Forces Central Command (CENTCOM). Up to 7,000 American troops are stationed across the small island state.

Sheikh Isa Air Base located on the island also houses American warplanes, spy aircraft and a U.S. special forces operations center. Washinton considers Bahrain a "major non-NATO ally".

Bahrain has long voiced concern over the expansion of Iran's sectarian ideology across the Middle East and joined a U.S.-led naval coalition established last year to keep Iran in check in the Persian Gulf.

Ali Saeedi, the Iranian supreme leader's representative to the IRGC, told the official Islamic Republic News Agency on Saturday that they had missiles aimed at 35 U.S. bases in the region, the closest being in Bahrain.

Iraq

U.S. military involvement in Iraq goes back to the 1991 Gulf War when it imposed no-fly zones over the country.

The U.S. would later invade Iraq in 2003 as part of its highly-criticized war on terror campaign, establishing a presence of ground troops.

After then-Iraqi President Saddam Hussein was overthrown and executed in December 2006, Washington sought to withdraw in 2011.

However, the Pentagon redeployed thousands of troops three years later following the partial takeover of the country by the Daesh/ISIS terror group.

Though both helped Iraqi security forces expel the Daesh/ISIS threat, the U.S. and Iran have frequently accused each other of hostile acts.

Washington's "maximum pressure" campaign against Tehran and random rocket attacks by Iran-backed groups against U.S. military targets in the region threaten the stability of Iraq and neighboring countries at a time when two hostile foreign powers -- both calling Iraq an ally -- lock heads on Iraqi territory.

Most Iraqis express deep opposition to both American and Iranian influence in their country, staging mass protests against their government's passive policies for months.

Following Soleimani's death, some Iraqis were seen celebrating while another big crowd turned out to mourn.

There are approximately 6,000 U.S. Special Operations Forces in Iraq, spread across seven different facilities, and another five bases in the country's northern semi-autonomous Kurdish region.

Kuwait

Another major non-NATO ally to the U.S., Kuwait began hosting U.S. forces after the defeat of invading Iraqi forces during the 1991 Gulf War.

As one of the Pentagon's most important Middle East hubs, Kuwait hosts about 13,000 American troops, with 3,000 more en route.

Kuwait International Airport houses the U.S. military's largest air logistics center in the Middle East. Kuwait, denying on Sunday that the U.S. drone that killed Soleimani originated from its territory, demanded stability in the region and maintains formal relations with Iran. 

Jordan

The Kingdom of Jordan has long been a Western ally and, along with Egypt, is the only other Arab country to have an existing peace agreement with Israel.

Jordan hosts about 3,000 U.S. troops as part of the anti-Daesh/ISIS mission.

Oman

Oman, with a strategic position near the Strait of Hormuz, maintains diplomatic ties with Iran and claims neutrality in regional matters. Yet, the U.S. military has access to the country since 1980.

It hosts about 600 U.S. troops.

Saudi Arabia 

The U.S. pulled troops out of Saudi Arabia after the Sept. 11, 2001 terror attacks and the 2003 invasion of Iraq. U.S. military presence in Saudi Arabia since the Gulf War has drawn strong criticism from Muslims across the region, who view this as an insult to Islam's two holiest sites of Mecca and Medina.

Last summer, U.S. officials said fighter aircraft, air defense missiles and more than 500 American troops would return to Riyadh's Prince Sultan Air Base due to increased tensions with Iran.

United Arab Emirates

The Jebel Ali port in Dubai is the most-frequented port of call for the U.S. Navy outside the country's own coasts.

The U.A.E. houses some 5,000 U.S. service members, many at Abu Dhabi’s Al Dhafra Air Base. American drones and F-35 fighter planes are also stationed at this base.

Turkey

The U.S. Air Force has access to the Incirlik Air Base in Adana, southern Turkey, just 110 kilometers (68 miles) from the Syrian border.

The base proved a strategic asset since its establishment in 1954 as it played major roles during the Cold War, 1990-1991 Gulf War, and U.S.-led Operation Inherent Resolve targeting Daesh/ISIS elements in Syria and Iraq.

However, many U.S. lawmakers are considering to shut the base down in response to Turkey's independent foreign policy agenda in the region, which they claim are not in line with U.S. interests. Ankara, in return, accuses the U.S. of supporting the YPG/PKK terror group in northern Syria at the expense of NATO-ally Turkey's national interests.

Syria 

Despite repeated announcements by Trump last year that U.S. forces would withdraw from Syria, in the context of the pullout of American troops from northern Syria, the New York Times reported in October 2019 that the Pentagon was planning to "leave 150 Special Operations forces" at the al-Tanf base in the south of the country.

A total of roughly 800 U.S. troops are stationed in the country, with most being repositioned to the resource-rich eastern region in a bid to "secure the oil", according to President Donald Trump.