NATO on Wednesday defended the number of military exercises it has staged as a response to "growing Russian aggression" and refuted suggestions that they were helping make war in Europe more likely.

The alliance was reacting to a warning from a London-based think tank about the risks from a sharp increase in Russian and NATO war games since the conflict between the Ukrainian government and pro-Russian separatists flared up in April last year.

Turkey's foreign minister said Monday that Kurdish rebels "never respected" the peace process with Ankara, with a ceasefire now in tatters after a series of attacks and cross-border offensives.

Militants from the Kurdistan Workers' Party (PKK) -- who have waged a decades-long insurgency in southeastern Turkey -- "never ended their terrorist acts", Mevlut Cavusoglu said during a visit to Lisbon.

Ambassadors of NATO states will meet on Tuesday at Ankara's request for talks on a spike in violence between Turkey, the Islamic State group and PKK Kurdish militants, the military alliance said Sunday.

"Turkey requested the meeting in view of the seriousness of the situation after the heinous terrorist attacks in recent days, and also to inform Allies of the measures it is taking," the NATO statement said.

NATO head Jens Stoltenberg warned Tuesday that Russian plans to deploy 40 new nuclear ballistic missiles announced by President Vladimir Putin were part of a dangerous pattern of behavior by Moscow.

"This nuclear saber-rattling by Russia is unjustified, destabilizing and it is dangerous," Stoltenberg said after a meeting with European Commission head Jean-Claude Juncker.

Russia was conducting huge and unexpected war games on Tuesday, coinciding with a Nato drill in the Arctic at a time of heightened tensions in the region.

The snap check launched on the orders of President Vladimir Putin involved up to 700 units of military hardware, 12,000 troops and up to 250 aircraft, the defense ministry said.

The Islamic State group is recruiting fighters in Afghanistan, the commander of foreign forces in country has said, but they are not yet operational. 

There have been fears of IS group making inroads in Afghanistan since U.S.-led NATO forces ended their combat mission late last year, after 13 years of fighting insurgents. 

NATO on Wednesday expressed alarm over a "wide-ranging" military build-up by Russia in Crimea, as well as talk that Moscow could even install nuclear weapons on the annexed Black Sea peninsula.

A statement issued during two days of talks by the military alliance's top diplomats, in the Turkish resort of Antalya, said "we do not and will not" recognize Russia's 2014 annexation of Crimea from Ukraine.

NATO and Afghan leaders on Wednesday agreed on a framework for a future joint military-civilian presence in Afghanistan when the alliance's current mission ends, NATO's Secretary General Jens Stoltenberg said.

While the new mission would have a military component it would notably be led by a civilian, Stoltenberg said after a session of the NATO foreign ministers meeting in the Turkish city of Antalya attended by Afghan Foreign Minister Salahuddin Rabbani.

Turkey on Tuesday said nothing can justify Russia's actions in Ukraine and other ex-Soviet states, in a rare strong criticism of its increasingly close ally ahead of a NATO meeting.

Turkish Foreign Minister Mevlut Cavusoglu, whose country is a key member of NATO, said Ankara was prepared to play a "constructive role" in the disputes between Russia and the West over Ukraine.

Turkey on Tuesday called for determined action from NATO member states against the "significant" threat posed by Islamic State jihadists who have taken swathes of Iraq and Syria up to its borders.

Foreign Minister Mevlut Cavusoglu said in Antalya that the threat from IS to the south of the NATO alliance's borders would be a key issue when its top diplomats hold a two-day meeting from Wednesday in the southern resort city.