NATO strongly backed Turkey's fight against Islamic State militants in Syria at emergency talks but some countries expressed concerns that strikes on Kurdish fighters could torpedo peace talks with the rebels.
The rare meeting held at Turkey's request came as an uncompromising President Recep Tayyip Erdogan said he could not continue negotiations with the Kurds amid attacks on Turkish targets.
Turkish jets later hit Kurdish militants in southeastern Turkey after the group fired on security forces, the army said, stepping up a campaign that Ankara has launched in parallel with its strikes on IS, despite the Kurds' bitter opposition to the jihadists.
"All allies expressed their strong support for Turkey and we all stand together in solidarity with Turkey. We strongly condemn the terrorist attacks," NATO chief Jens Stoltenberg said after the meeting of the alliance's ambassadors in Brussels.
Stoltenberg said Turkey had not asked for military help -- the alliance's only Muslim member has the second largest armed forces in NATO after the United States -- and he welcomed its increased effort against IS.
Turkey's parliament is due to hold an emergency meeting Wednesday to discuss security threats.
- Suruc suicide bombing -
Ankara requested Tuesday's meeting of all 28 North Atlantic Treaty Organization nations after a devastating suicide bombing blamed on IS militants in the largely Kurdish border town of Suruc last week in which 32 people were killed.
The Kurds, however, suspect the Turkish government of colluding with IS -- a charge Ankara categorically denies -- and in the aftermath of the attack the outlawed Kurdistan Workers' Party (PKK) claimed several deadly strikes against police.
Once-reluctant Ankara then launched attacks against IS targets in Syria and Kurdish positions in northern Iraq, despite the fact that Kurdish forces have won some of the biggest military successes against the jihadists.
Turkey also agreed with the United States to create an "IS-free zone" in northern Syria and dropped its previous refusal to let US aircraft use its Incirlik airbase to launch attacks on the jihadists.
Erdogan -- whose relations with his Western allies have been bedevilled by human rights concerns -- insisted Ankara would press its attacks to the full and said he considered peace talks with the PKK dead in the water.
"It is not possible to carry on the (peace) process with those who target our national unity and brotherhood," Erdogan told reporters before leaving on a visit to China.
"Any step back is out of the question."
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Erdogan added that a safe zone would help the return of 1.7 million Syrian refugees in Turkey.
The violence continued on Tuesday, with a Turkish army sergeant shot dead by a Kurdish militant near the Iraqi border, the army said.
Two Turkish F-16 jets later made "direct hits" on PKK targets in a mountainous region bordering Iraq, the army said.
The air strikes are believed to the first on Kurdish militants inside Turkey since a 2011 botched raid by F-16 jets that killed 34 civilians, mainly cigarette smugglers.
- Sudden change of course -
Ankara, which along with its Western allies officially considers the PKK a terrorist organisation, launched peace negotiations with the group's jailed leader Abdullah Ocalan in late 2012 and agreed a truce.
The sudden change of course in recent days has raised questions in Western capitals over whether Ankara, fearful of seeing a Kurdish state emerge on its southern border, is more interested in limiting Kurdish capabilities than in tackling IS.
German Defence Minister Ursula von der Leyen said Tuesday she had told her Turkish counterpart that Berlin backed Ankara in the fight against IS but had "concerns over the intervention against the PKK".
"I said forcefully that in any peace process there had to be restraint, and that the peace process with the Kurds in Turkey should not be disturbed nor abandoned," von der Leyen said during a trip to Mali.
The Netherlands ambassador to NATO, Marjanne de Kwaasteniet, said "reconciliation should continue" between Turkey and the PKK.
The European Commission said its president Jean-Claude Juncker meanwhile called Turkish Prime Minister Ahmet Davutoglu at the weekend to back "robust action against IS", but "stressed the need for proportionality in all actions against the PKK".
Around 30 Kurdish representatives rallied outside the European Parliament in Brussels as the NATO talks were taking place.
"Turkey is not waging war against IS but against the Kurdish people," said Zubeyir Aydar of the Kurdish National Congress.