Ng nh Nhu (listen; 7 October 1910 2 November 1963; baptismal name Jacob) was a Vietnamese archivist and politician. He was the younger brother and chief political advisor of South Vietnam's first president, Ng nh Dim. Although he held no formal executive position, he wielded immense unofficial power, exercising personal command of both the ARVN Special Forces (a paramilitary unit which served as the Ng family's de facto private army) and the Cn Lao political apparatus (also known as the Personalist Labor Party) which served as the regime's de facto secret police.

In his early age, Nhu was a quiet and bookish individual who showed little inclination towards the political path taken by his elder brothers. While training as an archivist in France, Nhu adopted the Roman Catholic ideology of personalism, although critics claimed that he misused that philosophy. Upon returning to Vietnam, he helped his brother in his quest for political power, and Nhu proved an astute and ruthless tactician and strategist, helping Dim to gain more leverage and outwit rivals. During this time, he formed and handpicked the members of the secret Cn Lao Party, which swore its personal allegiance to the Ng family, provided their power base and eventually became their secret police force. Nhu remained as its head until his own assassination.

In 1955, Nhu's supporters helped intimidate the public and rig the 1955 State of Vietnam referendum that ensconced his elder brother, Dim, in power. Nhu used the Cn Lao, which he organised into cells, to infiltrate every part of society to root out opposition to the Ng family. In 1959, he organized a failed assassination attempt via mail bomb on Prince Sihanouk, the prime minister of neighbouring Cambodia, with whom relations had become strained. Nhu publicly extolled his own intellectual abilities. He was known for making such public statements as promising to demolish the X Li Pagoda and vowing to kill his estranged father-in-law, Trn Vn Chng, who was the regime's ambassador to the United States, after the elder man condemned the Ng family's behavior and disowned his daughter, Nhu's wife, Madame Nhu.In 1963, the Ng family's grip on power became unstuck during the Buddhist crisis, during which the nation's Buddhist majority rose up against the pro-Catholic regime. Nhu tried to break the Buddhists' opposition by using the Special Forces in raids on prominent Buddhist temples that left hundreds dead, and framing the regular army for it. However, Nhu's plan was uncovered, which intensified plots by military officers, encouraged by the Americans, who turned against the Ng family after the pagoda attacks. Nhu was aware of the plots, but remained confident he could outmaneuver them, and began to plot a counter-coup, as well as the assassinations of US Ambassador Henry Cabot Lodge Jr. and other American and opposition figures. Nhu was fooled by the loyalist General Tn Tht nh, who had turned against the Ng family. On 1 November 1963, the coup proceeded, and the Ng brothers (Nhu and Dim) were detained and assassinated the next day.

A letter bomb, also called parcel bomb, mail bomb, package bomb, note bomb, message bomb, gift bomb, present bomb, delivery bomb, surprise bomb, postal bomb, or post bomb, is an explosive device sent via the postal service, and designed with the intention to injure or kill the recipient when opened. They have been used in terrorist attacks such as those of the Unabomber. Some countries have agencies whose duties include the interdiction of letter bombs and the investigation of letter bombings. The letter bomb may have been in use for nearly as long as the common postal service has been in existence, as far back as 1764 (see Examples).