Above: Tactical fighters are pivotal to CAS operations.

Persistence and the responsiveness of aircraft matter in any battlespace, while precision of delivery and weapons effect to avoid fratricide and collateral damage also matter. Additionally, around the clock all-weather operations have become the norm. CAS is therefore relevant in military campaigns today, and tomorrow.
CAS is broadly defined as air attack on ground targets in direct contact with friendly troops. In contrast, Battlefield Air Interdiction (BAI) is when aircraft attack targets across the battlefield, often hundreds of kilometres from friendly troops. With indirect fire weapons of increasing range, the distinction between CAS and BAI will blur over time. In a Counter Insurgency (COIN) environment, the problems inherent in CAS and BAI operations are magnified by the disproportionate political damage arising from collateral damage.
Historically, CAS has been contentious because of the challenging demands of being responsive in time. If a ground unit is pinned down and taking losses from enemy fire every second of delay costs lives. The problem is magnified by the potential for fratricide, either from weapon collateral damage or targeting mistakes. Too large a weapon used may kill friendly troops just as surely as putting the weapon in the wrong place. A complicating factor for CAS operations is the pervasive global digital media, which can globally broadcast collateral damage incidents at unprecedented rates, providing a no less unprecedented advantage to propagandists acting for, or as proxies for the insurgent side.
Unlike earlier COIN campaigns, the Global War On Terror or Overseas Contingency Operation, in current bureaucratese, seldom involves large concentrations of insurgent infantry or the use of heavier weapons. The IED, AKM, RPG and MANPADS are the insurgent's weapons of choice in this campaign. More conventional tactics used in 2001 by Al Qaeda and Taliban forces in Afghanistan brought their annihilation by B-52H bombers armed with JDAMs and LGB-armed F-14D and F/A-18 fighters. A similar pattern emerged during the Iraqi insurgency with JDAMs, LGBs and laser guided Hellfire missiles inflicting heavy losses, especially in the Second Battle for Fallujah.
In modern CAS/BAI, the aircraft orbits well above the reach of all handheld weapons, and obliterates the target with a precision guided weapon, or accurate gunfire from altitude.