Since October 2001, NATO naval forces (comprising warships, submarines, aircraft and helicopters) have patrolled the Mediterranean as part of Operation Active Endeavour. They control the traffic of ships and escort merchant ships through the Strait of Gibraltar. The purpose of Active Endeavour is to help defend, disrupt and protect against terrorist activity in the Mediterranean Sea. This operation represents an important stage in the development of the North Atlantic Alliance. Establishing a stable and calm environment in the Mediterranean, a region of intense commercial traffic, is essential to the security of the Alliance. 65% of oil and natural gas in Western Europe, is transported through the Mediterranean routes. Large pipelines connect Libya with Italy, Morocco with Spain. With this in mind, the NATO military forces systematically monitor the pipelines. Non-military ships flying the flag of NATO members also began to be escorted through the Strait of Gibraltar under Active Endeavour, since March 2003. The purpose of this decision was to prevent terrorist attacks like those that took place in 2000, in Yemen, against U.S. flag ships and in 2002 – against France flag ships. Since April 2003, NATO has been systematically inspecting suspicious ships. Under Operation Active Endeavour, Alliance ships and helicopters conducted several rescue operations, including the evacuation of workers from an oil rig and evacuation of crew members from sinking vessels. The presence of the NATO military forces in the Mediterranean waters has contributed to the close security cooperation between NATO and the Mediterranean countries (Algeria, Egypt, Israel, Jordan, Mauritania, Morocco, Tunisia), which, within the scope of  Active Endeavour, provide the Alliance with intelligence data regading the ships sailing in their regional waters. NATO’s enhanced presence in the Mediterranean is a guarantee of security and has a positive impact on shipping traffic. Active Endeavour also contributes to the development of trade and economic relations in the region. It needs to be highlighted that, along with NATO member states, partner countries are also involved in the operation.