Turkey's military operation in Syria will provoke "forceful" discussion at a NATO defence ministers' meeting Thursday and Friday but Ankara risks little from its allies because of its strategic position, diplomats said.
The issue looks certain to overshadow the meeting in Brussels, with Turkey isolated among the 29 member states because of its incursion this month against Kurdish fighters, considered "terrorists" by Ankara but which were key in the fight against the Islamic State group in Syria.
NATO Secretary General Jens Stoltenberg has refused to condemn Turkey, saying it has "legitimate security concerns" along its border with Syria.
On arrival Thursday, he confirmed the meeting "will address the situation in northeast Syria" where he said a Turkey-US "ceasefire" accord struck last week had reduced fighting.
Diplomats, however, described exchanges with Ankara's representatives as "frank". But they admitted that Turkey's location at the gates of the Middle East and next to Russia gave it a strategic value weightier than the objections.
Discussions among the ministers "are going to be forceful" but "there's no question of arguing," a high-ranking diplomat said.
"There is no question of sanctioning Ankara or excluding Turkey (from NATO) -- there is no procedure for that," the diplomat said.
US Defense Secretary Mark Esper, speaking at a think tank conference in Brussels just before the meeting, said Turkey was "heading in the wrong direction", especially with its deal struck this week with Russia to jointly patrol a "safe zone" in Syria it aims to set up.
"Turkey put us all in a very terrible situation and I think the incursion's unwarranted," Esper said.
He defended the withdrawal of US troops from northern Syria to leave a clear path for the Turkish operation.
"I was not about to put less than 50 US soldiers in between a 15,000-man-plus Turkish army preceded by Turkish militia and jeopardise the lives of those servicemen". Nor was he "about to start a fight with a NATO ally," he said.
US President Donald Trump on Wednesday summed up American strategy in Syria more bluntly, saying: "Let someone else fight over this long blood-stained sand."
Nevertheless, Turkey's recent actions, growing closer to Russia and threatening its European allies in NATO with a wave of refugees if they dared criticise the assault in Syria, have unnerved many in the transatlantic alliance.
Ankara has earned the ire of Washington for deciding to buy a Russian S-400 anti-aircraft defence system.
President Recep Tayyip Erdogan compounded concerns on Tuesday by agreeing with Russian leader Vladimir Putin to have Russian forces clear Kurdish militia out of Turkey's "safe zone" and deploy forces to jointly patrol it.
European NATO members are worried about the developments.
Germany has floated the idea of an international force with a European component to establish a security zone in northeastern Syria.
Its defence minister, Annegret Kramp-Karrenbauer, said she would raise the plan with her counterparts at the NATO meeting. The US has said it would welcome the initiative.
"It is important that international action to resolve this crisis is not limited to Turkey and Russia," German Chancellor Angela Merkel's spokesman told reporters on Wednesday.
"Europe must deal with current events taking place at the border of our continent because these are issues that directly affect several EU member states."
Stoltenberg said the German proposal would need UN approval to be implemented and therefore "needs to be discussed more in detail before any decision can be made".
