encountered by US forces during the Vietnam War. Their importance can be seen by the hard fighting sometimes engaged in by communist forces to protect those sites. However, when it became clear that defense was untenable, communist units typically withdrew without sentiment. Terrain Guerrilla warfare is often associated with a rural setting, which was indeed the case with the definitive operations of Mao and Giap, and the mujahadeen of Afghanistan. Guerrillas, however, have successfully operated in urban settings, such as in Argentina and Cyprus. In both cases, guerrillas rely on a friendly population to provide supplies and intelligence. Rural guerrillas prefer to operate in regions providing plenty of cover and concealment, especially heavily forested and mountainous areas. Urban guerrillas, rather than melting into the mountains and jungles, blend into the population and also depend on a support base among the people. Rooting guerrillas out of both types of areas can be difficult. Foreign support and sanctuaries Foreign support in the form of soldiers, weapons, sanctuary, or statements of sympathy for guerrillas is not strictly necessary, but it can greatly increase the chances of an insurgent victory. Foreign diplomatic support may bring the guerrilla cause to international attention, putting pressure on local opponents to make concessions or garnering sympathetic support and material assistance. Foreign sanctuaries can add heavily to guerrilla chances, furnishing weapons, supplies, materials, and training bases. Such shelter can benefit from international law, particularly if the sponsoring regime is successful in concealing its support and in claiming plausible deniability for attacks that are by operatives based in its territory. The VC and NVA made extensive use of such international sanctuaries during their conflict, and the complex of trails, way-stations and bases snaking through Laos and Cambodia (the famous Ho Chi Minh Trail) was the logistical lifeline that sustained their forces in South Vietnam. Another case in point is the Mukti Bahini guerrillas, who fought alongside the Indian Army in the 14-day Bangladesh Liberation War in 1971 against Pakistan, which led to the independence of Bangladesh. In the post-Vietnam era, al-Qaeda also made effective use of remote territories, such as Afghanistan under the Taliban regime, to plan and execute its operations. That foreign sanctuary eventually broke down with American attacks against the Taliban and al-Qaeda after operatives pulled off the September 11, 2001 attacks. Guerrilla initiative and combat intensity As they can choose when and where to strike, guerrillas usually