SUMMARY
The United States of America emerged from the Second World War as one of the world's two superpowers and has remained among the most militarily engaged states in the world ever since. Its involvement in armed conflict has mostly taken place abroad, frequently as a secondary warring party supporting other governments or armed movements rather than as a direct combatant at home.
2025
UCDP recorded no organized violence on the territory of the United States in 2025. Abroad, however, the United States remained heavily engaged militarily, coded by UCDP as a secondary warring party in six active conflicts during the year.
Its most direct involvement came in the interstate war between Iran and Israel, which it joined on Israel's side. The rest of its involvement was part of longer campaign against the Islamic State (IS) in support of the governments of Somalia, Syria, Iraq and Nigeria. It was also a secondary warring party to the government in Somalia against Al-Shabaab.
Organized Violence
After the end of the Cold War, the USA established itself as global hegemon and pursued several military engagements around the world with the aim of creating a “new world order” based on liberalism and democracy. Subsequently, the USA intervened as a secondary warring party to the Kuwaiti side in the so called Persian Gulf War of 1991 when Iraq invaded Kuwait (see Government of Iraq – Government of Kuwait). It also provided military support to the UCK when it led the NATO coalition in the Yugoslavia/Serbia intra-state conflict over Kosovo in 1999 (see Government of Serbia (Yugoslavia) – UCK).
However, the al-Qaida attacks on New York City and Washington on 11 September 2001 brought global terrorism into the limelight for the USA (see al-Qaida – Civilians). These events resulted in President George W. Bush’s declaration of a "War on Terror", with the core aim of dismantling the terrorist network al-Qaida (the Base), and has resulted in several armed conflicts involving the USA. Starting in 2001 the USA, as a primary warring party, has engaged the terrorist network al-Qaida in what has been deemed an intra-state conflict with foreign involvement. However, this untraditional conflict has largely been played out in Afghanistan and Pakistan rather than within the territory of the USA (see Government of United States of America – al-Qaida).
Knowing that the bulk of al-Qaida’s network was based in Afghanistan, the US has been particularly involved there under the “War on Terror” banner. When the Government of Afghanistan, then under the Taleban regime, refused to extradite al-Qaida leaders harboring in Afghanistan without more convincing evidence of their involvement in the 9/11 attacks being provided first, the US government responded by launching "Operation Enduring Freedom" on 7 October 2001 instead. Allying with the Government of the United Kingdom, the US initiated an interstate conflict to remove the Taleban regime (see Government of Afghanistan - Government of United Kingdom, Government of United States of America). In addition, the USA also provided secondary warring support to the UIFSA in their intra-state conflict against the Taleban regime in 2001 (see Government of Afghanistan – UIFSA). From 2003, secondary support was provided again, this time to the new transitional Afghan government in its intrastate conflict against the Taleban after it fell from power and organized as a rebel group (see Government of Afghanistan – Taleban).
The USA also became involved in Iraq, first as a primary warring party in the 2003 inter-state conflict when it combated Saddam Hussein’s regime (see Government of Australia, Government of United Kingdom, Government of United States of America - Government of Iraq) with the result of the latter’s fall. The following year, it bolstered the new Iraqi regime by being a secondary warring party to the Government of Iraq as violence persisted in the form of an intra-state conflict beginning in 2004 (see Iraq:Government). In the context of this conflict, US troops also engaged in violence against Iraqi civilians (see Government of Iraq – Civilians).
Within Syria, the USA, together with Saudi Arabia, Jordan, Bahrain and United Arab Emirates, began carrying out airstrikes against IS as a continuation of the “War on Terror” in 2014. Since the USA was seen as a secondary warring party to Iraq, all attacks carried out by USA and its coalition partners against IS were coded as part of the Government of Iraq-IS dyad, regardless of geographical location. In addition, the USA has also provided secondary support to the SDF for its non-state based conflict against IS in Syria (see IS – SDF) and Government of Iraq – IS).
Prior to the Cold War, the unrivaled economic and military resources of the United States of America enabled it to resolutely emerge as a global superpower alongside Russia (then the Soviet Union) at the end of the Second World War. In the immediate post-war period, hopes of peace and security were high worldwide. However, that possibility quickly faded as the relatively cooperative relationship that had existed during the Second World War between the USA and United Kingdom on the one hand and the Soviet Union on the other, began to disintegrate a couple of years after the Allied victory. The resultant Cold War was an approximately 40 year-long political, military and economic confrontation between the USA and the Soviet Union and their respective allies. It never escalated into direct military confrontation between the superpowers, but involved an unprecedented arms race with both nuclear and conventional weapons as well as plethora of proxy conflicts (i.e. when two powers use their allies to fight one another).
The central USA foreign policy doctrine in the Cold War era came to be the 1947 Truman Doctrine which asserted that the USA was to support foreign nations who desired to acquire or maintain political freedom as defined by the USA. The doctrine’s accompanying strategy was containment, which postulated that to contain the USSR, the USA needed to apply “counter pressure” wherever in the world the USSR applied pressure. Equipped with this rationale the USA engaged in several armed conflicts in this period (particularly in South East Asia and in the Western Hemisphere). Nonetheless, as was characteristic for the Cold War Era, the USA was primarily engaged by providing secondary warring support to governments or rebel movements that rejected communism.
Hence the USA provided secondary warring support to the South Korean government, first in 1948-1950 in an intra-state conflict against leftist insurgents and subsequently in 1950-1953 when South Korea and North Korea clashed in an inter-state conflict. The USA likewise intervened as a secondary warring party in 1954 and 1958 in the inter-state China-Taiwan conflict, on the side of Taiwan. In spite of great domestic opposition, the USA government provided secondary warring support to the Republic of Vietnam in 1962-1964 against the domestic Communist forces and in 1965-1975 in the inter-state conflict with the Democratic Republic of Vietnam. Both the governments of Laos and Cambodia were bolstered by USA warring support in their respective intra-state conflicts (the former received the assistance in 1963-1973 and the latter in 1970-1973) against leftist armed groups.
The USA was likewise, if not more, concerned about containing “the communist threat” in its own Western hemisphere. Therefore, it became involved, most often clandestinely, in several conflicts in Latin America and the Caribbean throughout the Cold War. Exceptionally, the USA waged a brief extra-state conflict in Puerto Rico (which is a self-governing unincorporated territory of the United States) in 1950 against PRNP (Puerto Rican Nationalist Party). Supporting the overthrow of Fidel Castro’s regime, the USA militarily backed up a formation of counter-revolutionary exile-Cubans which executed the foiled 1961 Bay of Pigs Invasion. In the 1980s the Reagan administration took renewed interest in the Americas. This interest manifested itself for example in the short 1983 inter-state conflict with Grenada, a Caribbean island which had recently experienced a successful hard-line leftist coup to the disapproval of USA. Upon invading the island with 8,000 troops, the USA was victorious and a more moderate regime was put in place. The USA similarly invaded Panama and waged a short inter-state war there in 1989, resulting in the ouster of Panamanian President Manuel Noriega.
Since 1946 the United States of America has been involved in the extra-state, interstate and intrastate categories of UCDP organized violence.
