The United Nations special envoy for Yemen, Hans Grundberg, has warned that 'four years of calm can be lost in a few weeks of escalation.'

Grundberg's warning follows the release of 73 UN and NGO staff members who had been detained. Tom Fletcher, the UN's under-secretary-general for humanitarian affairs, described their release as an 'appeal to our shared humanity.'

Four years of calm can be lost in a few weeks of escalation.

Appeal to our shared humanity.
— Tom Fletcher, UN under-secretary-general for humanitarian affairs