NATO is starting military maneuvers in Spain, Italy and Portugal in what are the alliance's largest exercises since 2002 - widely seen as a display of force for Russia to see.
NATO has planned to extend its 14 year military presence in Afghanistan as unrest in the country intensifies.
The drills come as tensions increase between the 28 country alliance and Russia over Moscow's alleged violations of Turkey's airspace and continued airstrikes in Syria.
The NATO exercises known as Trident Juncture involve 36,000 troops, 140 aircraft and more than 60 ships from 30 countries including non-Nato member Ukraine.
NATO Spokesperson, Oana Lungescu, said the drill is one in a series to ensure allies are ready and capable to react in the event of a crisis.
"Of course this exercise takes on additional significance because of the changed security environment that we find ourselves in- the rising challenges from both the south and the east to which NATO is adapting and continues to adapt," said Lungescu.
The maneuvers are testing a fast-reaction force created after Russia annexed Crimea from Ukraine in 2014. The force of 5,000 is designed to deploy in less than a week if necessary.
General Hans-Lothar Domrose is the commanding officer for Trident Juncture. He said the maneuvers give the alliance members an important opportunity to work together.
"Well let me take the analogy of a football player. They are all super. They have a goal keep. They have strikers, but they have to form a team, and now when they come together they need training to win next Sunday's match. The same is true for NATO. All the forces that will be deployed to Italy, Spain and Portugal are excellent national forces, but I have to bring them under the NATO umbrella because only when we train then we can achieve a lot," said Domrose.
Although it was organized well before Russia's recent military actions in Syria, which have caused major contention between Moscow and the alliance, many observers say NATO is using the exercise as an opportunity to showcase its military might.
Other observers say they NATO must address all the threats in its neighborhood.
Ian Lesser, Director of the Brussels office of the German Marshall fund, said "But it is, in fact, not just about Russia in the east. It's also about a much less direct, less focussed but nonetheless less challenging set of problems in the South for crisis management, counter terrorism, surveillance, border control, the whole set, maritime security, human security, energy security- the whole set of issues that are emanating from the South. I think the alliance is keen to demonstrate the capacities it has and the ones and the ones that it will build are just as applicable, just as useful looking towards the Mediterranean."
Russia, who performed exercises in the Mediterranean earlier this year, was invited to observe the exercises.
In the meantime, NATO announced it intends to keep it's military forces in Afghanistan over concerns about the ability of the Afghan national forces to fight a resurgent Taliban.
