Peter Klingberg's Foreign-Policy Cycles

In 1952, historian Frank L. Klingberg identified some cycles of United States foreign policy, cycles much like Arthur Schlesinger's US history cycles. From The Cycles of American History, "A cyclical rhythm exists in foreign policy as well. Over thirty years ago Frank L. Klingberg analyzed what he called 'the historical alternation of moods in American foreign policy.' He uncovered a periodic swing between 'extroversion'--a readiness to use direct diplomatic, military or economic pressure on other nations to gain American ends--and 'introversion'--a concentration on concerns of the national community. Examining wars, annexations, armed expeditions, naval expenditures, presidential statements and party platforms, Klingberg in 1952 identified seven alternations since 1776 ..." Some later authors identify more alternations, and these also are included here.

The Cycles
Extroverted phases usually last about 27 years, and introverted ones about 21 years. By this timetable, the US's next introverted period should start around 2016 and the next extroverted one about 2037. It seems that the US is indeed headed toward introversion, with little desire for big military adventures, and not much desire even for small ones.
 * 1776 - 1797 -I- Revolution, establishment of government
 * 1798 - 1823 -E- French naval war, Louisiana Purchase, War of 1812
 * 1824 - 1844 -I- Nullification crisis of South Carolina, Texas question
 * 1845 - 1870 -E- Texas and Oregon annexations, Mexican War, Civil War
 * 1871 - 1890 -I- Lack of participation in the European powers' Scramble for Africa
 * 1891 - 1918 -E- Spanish-American War, World War I
 * 1919 - 1939 -I- League of Nations rejection, Neutrality Acts
 * 1940 - 1967 -E- World War II, Cold War, Korean and Vietnam Wars
 * 1968 - 1988 -I- Vietnamization, détente, fall of the Soviet Union
 * 1989 - ???? -E- Post-Cold-War assertion, Gulf War, War on Terror

A counterargument to these cycles is the American Indian wars, wars that occurred during both extroverted and introverted phases. However, these wars were inside the US's claimed territory, not with big nations outside the US. Also, the Civil War was an internal war, but it was a big and costly one, one that killed more Americans than any other war.

Also, Ronald Reagan was very evidently a frustrated extrovert, one who wanted to confront the Soviet Union, which he called an "evil empire" and the "focus of evil in the modern world". He showed his frustration by repeatedly complaining about the "Vietnam syndrome" introversion of many of his fellow Americans.

As with the Schlesinger cycles, one can plausibly speculate about what drives the Klingberg cycles. As with the Schlesinger cycles, each phase in the Klingberg cycles contains the seeds of its transition to the next one.

Introverted phases typically end as a result of real or perceived challenges from other nations. Challenges like the French naval war, Britain wanting Pacific Northwest territory, falling behind compared to European imperialism, and the rise of the Axis powers.

Extroverted phases typically end as a result of some big war. Americans then become unwilling to fight such wars for a while. The war of 1812, the Civil War, World War II, and the Vietnam. Could this be happening with the "War on Terror"?