The North Atlantic Treaty Organisation has now formally enlisted in the fight against Islamic State. It can begin by helping to stem the flow of refugees trying to reach Europe from North Africa.

This would be more than a humanitarian exercise; it would be a counterterrorism operation. Wherever refugees gather in hopelessness, violent extremists have a fertile recruiting ground. And the number of refugees is staggering.

Nearly 200,000 people fleeing violence and poverty tried to cross the Mediterranean last year, and at least 5,000 died in the attempt.

The United Nations estimates there are more than half a million refugees, asylum seekers and displaced people in Libya alone. Neither the fractured Libyan Government nor the European Union can cope with the numbers, leaving hundreds of thousands of people in makeshift refugee camps — some of which are controlled by human traffickers and resemble concentration camps, according to a German Government report.

Those who make it across the Mediterranean do not fare much better.

Most end up in overcrowded camps in Italy, where social services are lacking and applications for asylum languish. Those intercepted in Libyan waters are sent back. Sometimes the traffickers dump their human cargo in the sea to avoid capture.

So what can Nato do? With more than 700 ships at its disposal, a lot.

For starters, it can build on Italian-led Operation Sophia, which has saved thousands of lives but is woefully inadequate to the task.

Nato’s sophisticated surveillance capabilities, such as long-range patrol aircraft and satellite imagery, can monitor ports in Africa and the Middle East and aid in search-and-rescue efforts. Nato can also help the EU’s efforts to professionalise the Libyan coastguard.

The alliance can foster far more naval co-operation and intelligence sharing among its members, and with intergovernmental entities such as Interpol. This should also involve another underused asset: private shipping companies, which are obligated to respond to other vessels in distress. Nato could also encourage member states to build more camps on Mediterranean islands and could aid with construction, perimeter security, healthcare and the like.

Nato patrols in the Mediterranean could also provide a more direct benefit in the fight against terrorists: stemming the flow of arms from the Middle East to Islamist terrorists in North Africa. Islamic State already has a foothold in Libya and is trying to expand into Tunisia.

Two years ago, the civil war in Syria caused the exodus of millions, which set off a political crisis from Greece to Britain and created a lasting rift between Turkey and its Nato allies. That time, the alliance watched from the sidelines. Now, as fighting intensifies and conditions deteriorate in Syria, Nato cannot afford to make the same mistake.