With the Syrian government and rebel groups well into the second week of a “cessation of hostilities agreement” intended to pave the way for a peace process between the government of Bashar al-Assad and various Syrian rebel groups, we thought we’d update last year’s Readers’ Guide on the law of airstrikes. Particularly because the ceasefire doesn’t mean strikes by the US and others against the Islamic State in Iraq and the Levant (ISIL), the al-Nusra Front, and other “terrorist organizations” in Syria are coming to a close any time soon, as Jonathan Horowitz pointed out last week. Indeed, the ceasefire may actually sanction the US and other states’ continued use of military force against ISIL and the al-Nusra Front in Syria.

At least 12 countries have participated in airstrikes against ISIL targets in Syria since the US and a coalition of allies, including four Arab states, began regularly doing so in September 2014. The UK joined this effort in July 2015, conducting airstrikes despite Parliament’s previous vote against it. (Parliament changed its tune on the issue last December.) That same month, Turkey launched its first strikes against ISIL targets in Syria. In September 2015, France, Russia, and Australia all began airstrikes as well.

As the air war against ISIL has escalated, our contributors have analyzed the legal rationales and ramifications of bombing within Syria from a number of angles. Their posts (as well as some other resources) are collected and organized below.

Legal Framework: Right to Use Force

A Legal Map of Airstrikes in Syria (Part 1), Jonathan Horowitz sets out the legal reasons various states, including the US, have used to justify airstrikes in Syria. December 7, 2015.

A Legal Map of Airstrikes in Syria (Part 2), Jonathan Horowitz outlines the general rules of international law that regulate when a state can engage in airstrikes and reflects on the emerging legal patterns, trends, and challenges. December 8, 2015.

Legal Framework: How Force May Be Used

Targeting Tankers Under the Law of War (Part 1), Beth Van Schaack discusses whether ISIL oil tanker are lawful military objectives under customary international law. December 2, 2015.

Targeting Tankers Under the Law of War (Part 2), Beth Van Schaack analyzes the duty to warn civilian oil tanker drivers and its implications in several scenarios. December 3, 2015.

Are People in Islamic State Training Camps Legitimate Targets?, Elvina Pothelet examines whether individuals in terrorist training camps in Syria can be legitimately targeted and looks at what it takes to consider them has having a “continuous combat function” for the purposes of the international humanitarian law. March 4, 2016.

Country-Specific Strikes


France Maps out Its War Against the Islamic State, Anthony Dworkin offers an inside look into the French perspective on French military actions against Syria. November 19, 2015.

Where Will the Law of Self-Defense Go From Here?, Laura Dickinson reflects on France’s invocation of self-defense in the aftermath of the Paris terrorist attacks. November 20, 2015.

United Kingdom

Questions the Media Should Be Asking About DOD’s Latest Targeted Killing, John Reed discusses the legal and policy questions prompted by the UK’s targeted drone strike in Syria. September 1, 2015.

The Legal Questions About the UK’s Drone Strike in Syria, Noam Lubell lays out when and how lethal force can be used in Syria after the UK’s drone strike. September 10, 2015.

European Countries Are Edging Toward Their Own War on Terror, Anthony Dworkin on the implications of the UK’s drone strike against British citizens in Syria. September 11, 2015.

UK’s Legal Rationale for Drone Strikes Differs Fundamentally From US Rationale, Kate Martin examines the UK’s rationale for using drone strikes outside an armed conflict. September 25, 2015.

United States

Is the US Allowed to Control a Syrian Airfield?, Jonathan Horowitz explores whether the U.S. has a legal basis for controlling a Syrian airfield and whether that control changes the nature of the conflict. January 27, 2016.

Letters Submitted to the UN

Request for Assistance

Iraq request for US assistance to fight ISIL (September 20, 2014)

Article 51 Letters

United States, September 23, 2014 (here)

United Kingdom, November 26, 2014 (here) and September 7, 2015 (here)

Canada, March 31, 2015 (here)

Turkey, February 2, 2015 (here) and July 24, 2015 (here)

France, September 9, 2015 (here)

Australia, September 9, 2015 (here)