Which of the following is NOT a type of attack?

Reinforcement is not classified as a type of attack. In military terms, a reinforcement typically refers to the addition of troops, resources, or support to strengthen a position or unit that is already engaged in combat. It serves to bolster defensive capabilities or prepare for an offensive operation rather than being a direct action of aggression or assault.

In contrast, a counterattack is a specific response to an enemy's attack, aiming to regain the initiative and capitalize on an adversary's vulnerabilities. A feint is a deceptive maneuver designed to mislead an opponent about one’s real intentions, often used to distract or divert forces away from the actual point of attack. An ambush involves a surprise attack from a concealed position to catch the enemy off guard, emphasizing the element of surprise in offensive operations. Each of these options represents a tactical action meant to engage the enemy, while reinforcement aligns more with support and bolstering efforts, making it distinct from the other attack types.