: SOCOM (Special Operations Command) sets training and readiness standards, and defined a list of missions members of SOCOM could most likely expect to undertake. These are called "Special Operations Principal Missions." Naturally, SOCOM is always ready to do anything that needs be done (preferably legal.) 

Special Operations Principal Missions (two letter codes are a shorthand for that type of mission)

Direct Action (DA) operations are small scale, and usually short duration, offensive operations. This covers a lot of situations that involve seizing or destroying personnel or material. Tactical techniques used to carry out these missions include raids (a quick attack, followed by a retreat), ambush or a direct assault (a slower and more involved attack.) Commandos may also use mines or other explosive devices or call in fire from bombers or artillery. Also available for use are portable rocket or missile launchers. Sabotage is also a possibility. SEALs, for example, are trained to attach explosives to ships.

Combating Terrorism (CBT) is a highly specialized, resource-intensive mission. Some SOF (Special Operations Force) units maintain a high state of readiness to conduct CBT operations. This is what Delta Force was originally formed for (and it costs over a $100 million a year just to keep Delta in business). CBT activities include: anti-terrorism (AT, defending against terrorist attacks), counterterrorism (CT, going after known terrorists after they have attacked). Terrorism missions include things like recovering hostages or sensitive material from terrorist organizations, attacking of terrorist bases and infrastructure, and coming up with ways to reduce vulnerability to terrorism. 

Foreign Internal Defence (FID) is a basic Special Forces job and involves organizing, training, advising, and assisting military and paramilitary forces in a foreign nation. This is why Special Forces tend to specialize in a specific part of the world. To do this kind of work well, you should speak the local language and understand the local customs. 

Unconventional Warfare (UW) includes guerrilla warfare, subversion of hostile governments, sabotage, intelligence activities, evasion and escape (rescuing friendly pilots, or agents, from enemy territory), and other "war in the shadows" activities. During peacetime, these operations tend to be more political, while in wartime, the emphasis is on supporting military operations. For example, in peacetime, evasion and escape might involve getting friendly agents out of a place like Iraq. In war time, the same type of mission might involve going into Iraq to retrieve a downed pilot.

Special Reconnaissance (SR) is information gathering in far off, and usually dangerous, places. You send commandos to look around when satellites, recon aircraft or spies are unable to get the job done. There are several different types of SR missions, including; Environmental Reconnaissance (checking on terrain and climate in an area where larger military operations are planned), Armed Reconnaissance (locating and attacking targets of opportunity), Coastal Patrol and Interdiction (in an area you suspect hostile forces, or drug smugglers, are operating), Target and Threat Assessment (confirming where targets are in enemy territory), and Post-strike Reconnaissance (confirming targets in enemy territory were destroyed). 

Psychological Operations (PSYOP) uses whatever works to make foreign populations more pro-American. Basically propaganda and spin control against foreign governments, organizations, groups, and individuals. It's not all dropping leaflets and radio broadcasts. Often it's dealing directly with foreign journalists and planting stories. 

Civil Affairs (CA) assists military operations establishing, maintaining, influencing, or exploiting relations between military forces and civil authorities, both governmental and non-governmental, and the civilian population in a friendly, neutral, or hostile area of operation. 

Information Operations (IO) are really a spin off from PsyOps. Information War became all the rage in the Department of Defense during the 1990s. The only new wrinkle with Information War is that it pays closer attention to the Internet and information systems (something that sharp PsyOps operators would not have missed.) Recognizing this, IO stuff basically becomes something involving DA, SR, PSYOP and CA missions. All this is laid out in DODD S-3600.1 and JP 3-13 Draft. Now you know. 

Counterproliferation of Weapons of Mass Destruction (CP) is doing whatever it takes to seize, destroy, render safe, capture, or recover weapons of mass destruction (WMD). Commandos are ideal for monitoring and enforcing compliance with arms control treaties. Commandos can also under take SR and DA missions to locate and interdict sea, land, and air shipments of dangerous materials or weapons. SOCOM has the main responsibility for organizing, training, equipping, and otherwise preparing to conduct operations in support of American counterproliferation objectives.

In addition to their military value, Special Forces have a substantial psychological one as well. Enemy commanders know that the U.S. has the capability to put commandos and Special Forces in his rear area. Depending on who we are fighting, the possible presence of American commandos would cause some generals to send large numbers of troops to hunt them down. It's happened before. During the Vietnam war, two thousand Special Forces troops ran patrols in North Vietnamese controlled Laos that tied up over 30,000 North Vietnamese troops. American commandos have learned from that experience, and deliberately cultivate their reputation to generate the maximum fear in the minds of potential enemy commanders. And the fear is not entirely misplaced.