Forced displacement has many drivers but one of increasing concern is the use of explosive weapons in densely populated areas. Whether in Gaza during Operation Cast Lead in December 2008 to January 2009, during the final gruelling stages of the conflict in Sri Lanka, or in Aleppo and Homs in present-day Syria, the use of explosive weapons in densely populated areas encourages the forced displacement of hundreds of thousands of people.
Explosive weapons vary considerably, and include artillery shells, missile and rocket warheads, mortars, aircraft bombs, grenades and improvised explosive devices. Their common feature, however, is that they are indiscriminate within their zones of blast and fragmentation effect, which makes their use in populated areas highly problematic. Data collected across a range of conflicts, including Afghanistan, Iraq, Somalia and Yemen, reveal substantial and ongoing civilian suffering, both physical and psychological, caused by the blast and fragmentation effects of such weapons in populated areas. A study this year by Action on Armed Violence found that 87% of civilian deaths and injuries occurred in populated areas, including markets, schools, places of worship and private homes.
While it is difficult to attribute displacement directly to explosive weapons, their use has obvious implications for the displacement of civilians. To begin with, people are forced to flee areas under attack. If and when the fighting ceases or moves on, people are often unable to return due to the widespread destruction of, and damage to, their homes, sources of livelihood and essential infrastructure such as water and sanitation systems. Unexploded ordnance poses a continuing threat to civilians, including returning refugees and internally displaced persons, until it is removed.
The need to address this issue has recently risen up the international agenda, with ICRC, the UN Secretary-General, UN Emergency Relief Coordinator Valerie Amos, the Security Council and the General Assembly all noting or speaking out against the impact of the use of heavy weapons in population centres.
Civil society has also mobilised around the issue. In March 2011 an NGO coalition, the International Network on Explosive Weapons (INEW), was established, calling on states and other actors to strive to avoid the harm caused by explosive weapons in populated areas, to gather and make available relevant data, to realise the rights of victims, and to develop stronger international standards. Data collection and analysis are essential to deepening our understanding of the humanitarian impact of such weapons and to inform policy and practice; an important element in this would be more detailed analysis of the impact of explosive weapons in terms of causing and prolonging displacement.
Simon Bagshaw is Senior Policy Advisor, UN Office for the Coordination of Humanitarian Affairs, Geneva. The views expressed here are those of the author and do not necessarily reflect the views of the UN.
 Action on Armed Violence, Monitoring Explosive Violence: The EVMP Dataset 2011 (2012)
 ICRC, International Humanitarian Law and the Challenges of Contemporary Conflicts – Report prepared for the 31st International Conference of the Red Cross and Red Crescent (October 2011) p42
 See Report of the Secretary-General on the protection of civilians in armed conflict, S/2009/277 (29 May 2009), S/2010/579 (11 November 2010) and S/2012/376 (22 May 2012)