Single Integrated Operational Plan

Due in part to the lack of updated intelligence, nuclear planning increasingly focused on urban areas, which were easier to target and offered the potential for "bonus damage".

A committee led by General Hubert R. Harmon reported in May 1949 that even if all precisely hit their targets, the USSR would not surrender, its leadership would not be seriously weakened, and its military could still operate in Western Europe, the Middle East, and Asia.

[11][12]: 92 [9] The Harmon report had three immediate results: 1) It supported those within the United States Navy and elsewhere who criticized the centrality of atomic bombs and mass attacks on cities in American war planning.

One 1951 estimate foresaw 175 combat divisions allegedly prepared to simultaneously attack Western Europe, the United Kingdom, the Balkans, the Middle East, and North America.

In January 1950, he approved Kim Il Sung's proposal to conquer South Korea in what became the Korean War that summer, believing that victory there would discredit NATO.

The gambit backfired, however; despite their initial optimism the Communists were unable to defeat the US-led forces in Korea, and the war greatly increased Western military spending, for the first time making NATO a significant threat against the Soviets in Europe.

[9] A 1951 Warsaw Pact war plan for Poland was, Vojtech Mastny wrote, "unequivocally defensive" even while "NATO was haunted by the nightmare of armed communist hordes sweeping all but unopposed through Europe".

The three categories were codenamed BRAVO (blunting), ROMEO (retardation), and DELTA (disruption/destruction) of the Soviet ability to fight, and formed the basis of American nuclear targeting for almost a decade.

Based on extensive experience with nuclear strategy and targeting from his terms as Chief of Staff of the United States Army and NATO Supreme Allied Commander, the Eisenhower administration's NSC 162/2 of October 1953 chose a less expensive, defensive-oriented direction for the military that emphasized "massive retaliation", still primarily delivered by USAF, to deter war.

[14][11] The document formalized efforts begun under Truman to deploy newly developed tactical nuclear weapons small enough for most Air Force and Navy planes.

[11][17] LeMay disagreed with the JCS strategy of SAC making three separate attacks during a Soviet war: The first against airfields, the second on advancing troops, the third on cities and government centers.

[11] Other planners and USAF leadership believed that the Soviet Union could support its "immense armed forces for at least two years of intensive warfare" if industrial and government centers were not attacked.

Given the apparent impracticality of massive retaliation strategy, Army Chiefs of Staff Matthew Ridgway and his successor Maxwell Taylor argued within JCS that deterrence, instead of the "worst case" scenario of a full-scale nuclear war, should be the focus.

Massive retaliation remained the basis of American war planning;[11] the Killian Committee reported in 1955 that "We have an offensive advantage but are vulnerable to surprise attack" (emphasis in original),[19]: 191  and NATO estimated after the Hungarian revolution of 1956 that during wartime Western forces would retreat to the Rhine River within 48 hours.

In 1958, George Kistiakowsky, a key Manhattan Project scientist and Science Advisor in the Eisenhower Administration, suggested to the President that inspection of foreign military facilities was not sufficient to control their nuclear weapons.

Kistiakowsky's report, presented on 29 November, described uncoordinated plans with huge numbers of targets, many of which would be attacked by multiple forces, resulting in overkill.

[27]: 204  This first SIOP was extensively revised by a team at the RAND Corporation to become SIOP-62, describing a massive strike with the entire US arsenal of 3,200 warheads, totaling 7,847 megatons, against the USSR, China, and Soviet-aligned states with urban and other targets being hit simultaneously.

Weapon scientist, George Rathjens, looked through SAC's atlas of Soviet cities, searching for the town that most closely resembled Hiroshima in size and industrial concentration.

In less than fifteen years the United States had mastered a variety of complex technologies and acquired the ability to destroy most of an enemy's military capability and much of the human habitation of a continent in a single day.

Document JCS 2056/220 expressed the concerns of U.S. Marine Commandant David Shoup that the 1961 draft was inconsistent with a 1959 NSC policy guidance paper approved by Eisenhower.

Warsaw Pact plans continued to assume, however, that NATO would make a surprise attack which it would repulse into the west; the East Germans even prepared occupation currency and new street signs.

Our doctrines for the use of forces in nuclear conflict must insure that we can pursue specific policy objectives selected by the National Command Authorities at that time, from general guidelines established in advance.

Some of these systems eventually took the role of bargaining chips in arms control negotiations, although some, such as the B-2 "stealth" bomber remained highly classified as potential surprises in war.

If the NCA decides that the United States must launch nuclear weapons, the decision is communicated to the Chairman of the Joint Chiefs of Staff (CJCS) and through him to the National Military Command Center (often called the "war room") via the Presidential Emergency Satchel, informally referred to as the "football."

[39] As the orders go down the chain of command, always subject to the two-man rule, intermediate headquarters, and eventually the nuclear delivery platforms themselves, will receive Emergency Action Messages (EAM) to arm or launch weapons.

The circuitry controlling the PAL is deliberately positioned inside the warhead such that it cannot be reached without disabling the weapon, at a minimum, to a level that would require a full factory-level rebuild.

[12]: 72  The two countries began coordinating their plans for a Soviet attack in Europe after the Czechoslovak coup d'état of 1948, and later that year LeMay, as head of SAC, asked Tedder to allow the basing of American atomic weapons in Britain.

[50][45]: 161  In March 1957 the United States agreed to sell 60 Thor IRBMs,[48] in 1958 American hydrogen-weapon designs,[50] in 1960 the Skybolt ALBM, and after its cancellation the Polaris SLBM in 1962 as replacement.

Polaris was especially notable; British officials initially refused to believe the Americans' offer of state-of-the-art submarine missiles at a moderate price, and one scholar later called it "amazing".

[48] While its contribution to SIOP was minor compared to the enormous SAC arsenal of 1,600 bombers and 800 missiles, as RAF officers who worked with the Americans rose to leadership positions their experience benefited later partnerships between the two countries.

Montage of submerged submarine launch to the reentry of the multiple independently targetable reentry vehicles of a Trident missile
Atlas, a first-generation ICBM
A deputy's launch keyswitch in an old Minuteman ICBM launch control center. The commander's key was too far away to be turned by the same person.
E-6 Mercury