(Reuters) - Barack Obama arrived unannounced in Afghanistan on Sunday, his first visit to the war zone that could define his presidency since his election as commander-in-chief.
Following are key facts and figures about Afghanistan:
* Afghanistan is a landlocked country in Central Asia which shares borders with Iran, Pakistan, China, Tajikistan, Uzbekistan and Turkmenistan.
* Hamid Karzai has led the country since 2001, when U.S.-backed Afghan militia ended the five-year rule of the austere Islamist Taliban movement. He was re-elected for a second term in October 2009 after a highly contested vote which was mired in allegations of fraud.
* Afghanistan is one of the poorest countries in the world. Its population is almost 30 million. Life expectancy for both men and women is about 45 years.
* Some 42 percent of Afghans are Pashtun and 27 percent are Tajik. Hazaras and Uzbeks each account for 9 percent.
* There are two national languages, Pashto and Dari. Pashto, the language of the Pashtuns, is spoken in many parts of the south and east. Dari, a Persian language, is spoken mainly in the north and center.
* Only 28 percent of Afghans are literate.
* Violence has escalated in the past year as tens of thousands of additional foreign troops, mainly Americans, have been deployed in response to an escalating Taliban insurgency.
* Last month a United Nations report said the number of civilians killed in the war increased by 40 percent last year to a record 2,118 deaths -- 1,160 were killed by insurgents and 828 were killed by foreign forces.
* Violence is concentrated in the south and east of Afghanistan -- Helmand, one of the deadliest provinces, has been the target of two major U.S. Marine-led operations since U.S. President Barack Obama was elected. The latest, Operation Moshtarak, was launched last month to push the Taliban out of the town of Marjah.
* A total of 1,703 foreign troops have been killed in Afghanistan since the war started in November 2001. A record 520 were killed in 2009, the deadliest year so far in the war.
* The United States has lost 1,029 servicemen, Britain 278 and other NATO contributors 396, according to the iCasualties website (www.icasualties.org).
* There are nearly 120,000 foreign troops from 42 countries working under the NATO-led International Security Assistance Force (ISAF), established in December 2001.
* The United States has by far the most troops, with about 80,000, rising to 100,000 by the end of this year, triple the number when Obama took office.
* Other NATO allies have about 40,000 troops in total. Some countries have pledged thousands more, but some are withdrawing, including the Netherlands and Canada with about 5,000.
* Britain, with 9,500 troops, is the second largest ISAF contributor. Germany is next with 4,335 and France with 3,750, according to the most recent NATO figures.
* Last year, Obama said he wanted U.S. forces to begin withdrawing from Afghanistan from July 2011. U.S. officials say the withdrawal will be gradual, with the pace determined by conditions on the ground.
* According to the United Nations Human Development rankings for 2009, Afghanistan is ranked 181st out of 182 countries.
* Devastated by 30 years of conflict, Afghanistan's economy is dependent on foreign aid. International donors contribute seventy percent of the government's operating budget, which itself has been dwarfed by billions in aid spent directly by the donor states.
* Afghanistan's economic growth has also been stunted by high levels of corruption, which prevents aid from reaching ordinary Afghans.
* Public sector corruption in Afghanistan is seen as more rampant than any other country except Somalia, according to Transparency International.
* Afghanistan produces 92 percent of the world's opium, a thick paste from poppy used to make heroin, according to the latest U.N. Office on Drugs and Crime report.
* Helmand province in southern Afghanistan produces most of Afghanistan's opium poppy crop.
* About two thirds of the opium is turned into heroin before it leaves Afghanistan and goes on to feed some 15 million addicts, mainly in Russia, Iran and Europe.
* Opium cultivation in Afghanistan is directly linked to the Taliban insurgency. Since 2005, the Taliban have made up to $160 million a year from taxing cultivation and trade of the crop.
Sources: NATO, U.S. Forces, Reuters reports, U.N., World Bank, iCasualties.org; CIA World Fact Book, Transparency International.
Compiled by Golnar Motevalli; Editing by Peter Graff