actions are kept covert and intelligence functions stay clandestine. External support Many cell systems receive support from outside the cell. This can include leaders, trainers, and supplies (such as the Jedburgh assistance to the French Resistance), or a safe haven for overt activities (such as the NLF spokesmen who could operate in Hanoi). External support need not be overt. Certain Shi'a groups in Iraq, for example, receive assistance from Iran, but this is not a public position of the government of Iran, and may even be limited to factions of that government. Early U.S. support to the Afghan Northern Alliance against the Taliban used clandestine operators from the CIA and United States Army Special Forces. As the latter conflict escalated, U.S. participation became overt. Note that both unconventional warfare (guerrilla operations) and foreign internal defense (counterinsurgency) may be covert and use cellular organization. In a covert counterinsurgency mission, only selected host nation leaders are aware of the foreign support organization. Under Operation White Star, for example, U.S. personnel gave covert counterinsurgency assistance to the Royal Lao Army starting in 1959, this became overt in 1961, and finally ceased operations in 1962. Models of insurgency and associated cell characteristics Different kinds of insurgency differ in where they place clandestine or covert cells. Also, when certain types of insurgency grow in power, they deemphasize the cell system. They may still use cells for leadership security, but if overt violence by organized units becomes significant, cells become less important. In Mao's three-stage doctrine, cells are still useful in Phase II to give cover to part-time guerillas, but as the insurgency creates full-time military units in Phase III, the main units become the focus, not the cells. Different varieties of insurgency place their cells differently with respect to the existing government. The U.S. Army Field Manual FM3-07 distinguishes between varieties of insurgencies. Drawing on this work, Nyberg (a United States Marine Corps officer) describes four types of cell system (there is also a new type associated with transnational terrorist insurgencies): Traditional: The slowest to form, these are typically indigenous insurgencies that begin with limited goals. These are more secure than others, as they tend to form from people with preexisting social, cultural, or family ties. The insurgents resent a government that has failed to recognize tribal, racial, religious, or linguistic groups. They "perceive that the government has denied their rights and interests and work