BRUSSELS • Nato and its allies will today open their biggest military exercise in more than a decade in a show of strength in the central Mediterranean that takes place as Russia seeks to reassert itself across the water in the Levant.
While the exercises were planned long before Russia's build-up in Syria and are independent of events, the escalation of conflicts across North Africa and the Middle East is challenging Nato to react to multiple threats on its borders.
Committing 36,000 troops, 230 military units, 140 aircraft and more than 60 ships over five weeks, Nato and its allies want to show they can act in what British Defence Minister Michael Fallon has called "a darker and more dangerous world".
Some of the North Atlantic alliance's most senior officials will descend on an air base in southern Italy for an aircraft and helicopter showcase today, facing questions about how to react to a Russian threat no longer just on its eastern flank.
"Nato needs a strategy for its south, what is going on in this arc of instability, from Iraq to North Africa," said Britain's ambassador to Nato, Mr Adam Thomson.
"We also need to agree across the alliance on a long-term approach to Russia."
Russia, which conducted major exercises with more than 45,000 troops earlier this year and also held drills in the Mediterranean before conducting its air strikes in Syria, has been invited to observe the exercises.
After more than a decade of Nato-led combat operations in Afghanistan, the US-led military alliance is shifting to defend its territory, but the focus has been on its eastern border following Russia's annexation of Crimea last year.
Much of Nato's efforts have gone to reassure newer, eastern members that the alliance can deter a resurgent Russia. The 28-nation alliance has set up small command and control centres flying Nato flags from Estonia to Bulgaria, which can be backed up by rapid-reaction forces in the event of an attack.
But Libya's collapse, the rise of Islamic State in Iraq and Syria militants, Syria's civil war and the European Union's failure to stabilise its southern neighbourhood are now Nato's problems too, and Nato member Turkey shares borders with Syria and Iraq.
Russia's intervention in Syria has complicated an already complex scenario, testing the alliance's ability to deter a newly assertive Moscow without seeking direct confrontation. "We used to talk the eastern threat and the southern threat, but now the two have merged," said one Nato official.
Nato's efforts at deterrence in the east have produced one powerful new tool that exercises will test out: a 5,000-strong "spearhead" force that can deploy in less than a week.
The exercises, named Trident Juncture, aim to certify the spearhead force, which has air, maritime and special operations components, allowing it to become fully operational next year. It is part of a 40,000-strong rapid-reaction force.
Yet it is just one step, with some military experts calling it a "mobile trip wire" that would simply slow down any Russian advance.