ISTANBUL: The normally close ties between Turkey and Azerbaijan have come under strain, fuelled by a dispute over Baku's restrictions on the Islamic headscarf in schools and disagreements over Israel.
Public tensions have become evident in what has traditionally been a very close relationship between two nations which share a common language and whose bond is characterised by the slogan: One nation, two states.
Although the rhetoric has remained restrained at the top, senior officials have been more outspoken in their reactions.
On Monday, Oktay Saral, chief adviser to president Recep Tayyip Erdogan, shed his normal diplomatic reserve to denounce as "unacceptable" Azerbaijan's move to change school uniform regulations, banning anything that conflicts with the normal uniform or the secular principles of education.
"Wearing a headscarf ... is a requirement of faith!" he wrote on X.
"We expect Azerbaijan to reverse this mistake as soon as possible," he said.
The following day, the ruling Yeni Azerbaijan Party (YAP) hit back with a sharply worded statement denouncing Saral and MPs from Erdogan's AKP for their "populist and irresponsible statements".
"The recent disinformation campaign targeting Azerbaijan has become increasingly aggressive, systematic, and openly slanderous," it said.
The confrontation reflected sharp differences between Azerbaijan - one of the most secular states in the Muslim world - and the Islamo-conservative leadership in Ankara.
However, it also highlighted tensions over the growing rapprochement between Azerbaijan and Israel since Baku's 2020 Karabakh war with arch-foe Armenia, when the Israelis supplied them with drones and other weaponry.
Turkey's ties with Israel, by contrast, could hardly be worse, with Erdogan accusing Israel of genocide in Gaza and Ankara regularly releasing images of top-level talks with the leaders of Hamas, the Palestinian Islamist movement whose October 2023 attacks on Israel sparked its war in Gaza.
Baku more 'pragmatic'
Turkey's pro-government media has held little back, with the Yeni Safak daily denouncing the headscarf regulations as a gesture towards Israel.
"We firmly reject attempts to deliberately distort Azerbaijani-Israeli relations, portray these ties as supposedly exceptional, and use this as a basis for making political accusations against Azerbaijan," the country's ruling party said.
The sharp response underscores Azerbaijan's emergence as a regional middle power.
It is more willing to push back against Turkey as Ankara seeks to project influence from the Black Sea, increasingly ensnared by the Russia-Ukraine war, and an ever-more volatile Middle East.
"The changing geopolitical order in the greater Eurasia has enabled Azerbaijan to pursue a more pragmatic foreign policy," said Fuad Shahbazov, an independent political analyst, indicating that meant Baku now "categorically resists the attempts of external actors, even its ally Turkey."
However, on Friday, Kursad Zorlu, deputy head of Erdogan's AKP, said the two sides knew how to tackle problems "within the family" in what appeared to be a tacit call for online restraint.
At a regional summit in Baku on Thursday, Turkish foreign minister Hakan Fidan hailed "the unshakable bond ... between our leaders" despite being tested "in very difficult times".
Too much to lose
Observers agree the two nations share too much to risk a rupture.
"The sometimes-tense relations with Moscow and the Iran war happening next door mean that Baku cannot afford to alienate an otherwise good partner," Ivan Klyszcz of the Estonia-based International Centre for Defence and Security (ICDS) told AFP.
"Moreover, energy cooperation, ongoing well before the current spat, is too important for both parties," he stressed.
"For Turkey, Azerbaijan is an essential gate for Central Asia, a region ... seen by Ankara as strategic," he added.
Paradoxically, Baku seems to hold the cards, despite the fact that its population is ten times smaller than that of its ally.
"The litmus test of the Baku-Ankara axis will depend on the latter's further attitude and commitment to quickly get back on diplomatic tracks to handle this crisis," Shahbazov told AFP.
"Azerbaijan possesses energy leverage and access to the Central Asian region, giving it leverage over Turkey," he said.
This is a crucial asset, given Ankara's ambition to maintain its role as a transit hub between Europe and Asia.
Even so, points of friction remain.
On Friday, Baku said it had issued an "international arrest warrant" for a Turkish journalist working for the Sanliurfa Olay daily.
According to prosecutors, Celal Ciftci called for a "coup d’état" in Azerbaijan and promoted "religious extremism".