Brussels, Feb 5 (IANS/EFE): North Atlantic Treaty Organization (NATO) Secretary-General Jens Stoltenberg Thursday said strengthening an effective military presence in Eastern Europe is a purely defensive action that responds to Russia's behaviour in the Ukraine crisis and is consistent with the "international obligations" of the Atlantic Alliance.

"Everything we do, when it comes to increasing our own collective defence, by establishing an enhanced NATO Response Force and establishing the very high readiness force, the Spearhead Force, is something which is defensive," Stoltenberg told reporters on arrival at a meeting of NATO defence ministers in Brussels.

He added that this measure comes as "a response to what we are seeing from Russia over a period of time, and it is in full accordance with our international obligations".

The NATO meeting was called in response to alleged Russian involvement in Ukraine where pro-Moscow separatists are fighting the government, and the rise of the Islamic State terrorist group in Iraq and Syria.

The ministers plan to advance the preparation of a new high-strength force that could be deployed within days on the eastern borders of NATO, as well as the southern area, and the establishment of six units of command and control in six members in Eastern Europe.

"So this is something we do as a response to the aggressive actions we have seen of Russia violating international law and annexing Crimea," said Stoltenberg, who added that the organisation has to "adapt our forces when we see that the world is changing, more specifically the security environment".

The NATO chief noted that the military presence in the eastern part of the Alliance has already been increased, focusing on ensuring one of the fundamental principles of NATO: collective defence of its members.

Stoltenberg said the new NATO forces, known as the "the Spearhead Force" will allow the deployment of some 5,000 troops to deal with any threat, whether from the east, or Russia, or the south, the Middle East or Africa.

Moreover, the command and control units, which would consist of not more than 30 or 40 soldiers, would help provide the material needed to facilitate the deployment of more troops if necessary.

The six units would be deployed in Estonia, Latvia, Lithuania, Poland, Romania and Bulgaria.