UNHCR is still in shock over the brutal killing of staff member Zill-e-Usman, who was shot by unidentified gunmen in the Katcha Gari camp on the border of the Federally Administered Tribal Areas in the North-West Frontier Province – the third one of our staff to be killed in Pakistan this year. Four to five gunmen reportedly opened fire on Mr Usman as he was walking back from the camp administrative office to his car during a routine visit to the site.
There is no justification for attacks on humanitarian workers dedicated to the protection and care of the world's most vulnerable people. The deaths of two Afghans working for the UN yesterday, killed when a bomb hit their convoy on the outskirts of Kabul, offered another bloody reminder of these outrages, which are a tragedy that affects us all.
Today, the first ever World Humanitarian Day, we will pause to remember those two Afghans, Mr Usman and hundreds of other aid workers who have lost their lives while carrying out their duties around the world. The date is important: it was on 19 August 2003 that a massive bomb blast in Baghdad killed the-then UN Special Representative Sergio Vieira de Mello and 21 others.
In 2008 alone, 122 aid workers were killed in attacks, kidnappings and robberies. The fatality rate for international humanitarian workers actually exceeded that of UN peacekeepers.
This ongoing death toll raises fundamental questions about how we can ensure staff security in unstable environments. Globally, it reminds us of the major dilemma facing humanitarian agencies around the world – how do we meet the life-or-death needs of the world's most vulnerable people while making sure those who provide that help are kept safe?
Our ability to assist those who need it most is being severely tested by the shrinkage of the so-called "humanitarian space" in which we must work. And the nature of conflict is changing, with a multiplicity of armed groups – some of whom view humanitarian workers as legitimate targets.
Ensuring staff safety must be a top priority of every humanitarian organisation. This is non-negotiable. And yet there is a tension – and in some situations a contradiction – between the imperatives of staff safety and humanitarian action. UNHCR has continuously struggled to determine the "acceptable" level of security risk to which its staff members can be exposed.
As today's commemoration demonstrates, it is a truly terrible dilemma.
The writer is a former Portuguese prime minister and since 2005 has been the UN High Commissioner for Refugees