DUBAI, United Arab Emirates - In Libya, militias armed with shoulder-launched missiles are battling for control of the country's main airport. In Africa, the entire Sahel region is awash with weapons that include portable air defense systems leftover from the ouster of Moammar Gadhafi.
Then there's Syria's civil war, in which thousands of soldiers have defected and set up new battalions that have shot down military helicopters and jets. And in Iraq, the al-Qaida breakaway group that has taken huge swaths of territory seized weapons depots all along the way.
The world is pockmarked with volatile hot spots stretching from West Africa to Central Asia - a wide arc where commercial flights and airline passengers could potentially be at risk from ground-based weapons. Although counter-terrorism and weapons experts say the skies are largely safe, the downing of Malaysian Airlines Flight 17 illustrates the dangers inherent in any flight over unstable territory where sophisticated weapons might be available to militants.
On Tuesday, those risks were underscored by the U.S. Federal Aviation Administration, which told American airlines they were prohibited from flying to the Tel Aviv airport in Israel for at least 24 hours following the explosion of a rocket fired from Hamas-ruled Gaza in the latest war between Palestinians and the Jewish state.
The FAA has also prohibited flights in Libya, northern Ethiopia, North Korea and the eastern Ukraine Crimea region, and prohibited flights below a certain altitude in Iraq and Somalia.
The Malaysia Airlines jet was destroyed last week by a sophisticated surface-to-air missile as the plane cruised at an altitude of 33,000 feet (10,000 meters) above rebel-held battlefields in eastern Ukraine. All 298 people aboard were killed.
Some 50 to 60 countries around the world possess radar-guided high-altitude missile systems like the one that shot down the Boeing 777, according to John Pike, director of military information website GlobalSecurity.org.
A much smaller weapon that poses a more immediate threat are the hundreds of thousands of portable missile systems in circulation called MANPADS, which can strike targets flying as high as 15,000 feet, Pike and others said.
High-altitude missiles are much more expensive than MANPADS, much larger and require greater technical expertise.
"You can train someone to use a MANPAD in a good afternoon," said Peter Pham, director of the Michael S. Ansari Africa Center at the Atlantic Council.
Countries on the FAA's prohibited list that likely possess the kind of missile that brought down the Malaysian jet are North Korea, Israel and Ethiopia, Pike said. But those countries have armies that are in control of their arsenal.
The FAA has another list of places that it says pose a threat to U.S. aircraft, including Mali, Congo, Kenya, Yemen, Egypt's Sinai Peninsula, Syria, Iran and Afghanistan.
Of those places, Pike said, only Iran, Egypt and Syria possess sophisticated air defense technology, with Libya in question.
"The notion that a complex system like this could fall into the hands of irregular forces, who could turn around and start using it, well, the world that doesn't work that way," Pike said. "It's just too complicated."
A $40 million U.S. program to buy up loose missiles after the fall of Libya's Gadhafi helped secure just 5,000 of about 20,000 such weapons.
A report released in March by a United Nations panel of experts found that MANPADS from Libya have reached four conflict zones, including Chad and Mali. A MANPAD that militants in Egypt's Sinai Peninsula used to shoot down an Egyptian military helicopter this year originated in Libya, according to the report.
Libyan weapons were also found in Somalia, the Central African Republic and in parts of Nigeria where the militant group Boko Haram operates.
The Nigerian army has been unable to guard its ammunition, and Boko Haram regularly attacks military camps, including a main air force base in the east and the Maiduguri International Airport in December. Nigeria is not on any of the FAA's lists for prohibited or potentially hazardous countries.
However, there are concerns that Boko Haram militants may have acquired earlier versions of the Russian SA-7 shoulder-fired missiles that can hit low-flying aircraft within about three miles.
In 1998, rebels in Congo used a shoulder-fired SA-7 missile to shoot down a jetliner carrying 40 civilians. There were no survivors. A decade earlier, Afghan guerrillas shot down a Soviet-built passenger jet, killing all 29 people aboard.
Afghan Defense Ministry spokesman Gen. Mohammad Zahir Azimi said there have not been any incidents to suggest insurgents there possess high-altitude missile technology.
Many international commercial flights continue to fly normally over militant-held areas in western and northern Iraq.
A military intelligence official told The Associated Press that the Islamic State group and other Sunni militants who have overran Iraqi military bases do not have access to sophisticated anti-aircraft weapons. The official spoke on condition of anonymity because he was not authorized to speak to the media.
With so many armed conflicts across the world, it is unrealistic to expect airliners to avoid all these places, said Brian Jenkins of the Rand Corporation think tank.
"If there were to be a rule that simply said commercial airlines cannot or should not fly over any country where there's an ongoing conflict," he said, "we would be removing a huge amount of territory."