Deepening rifts between Turkey and the United States are fueling speculation Turkey is being given further impetus to strengthen ties with nearby Russia.
Senior Turkish officials met with their Russian and Iranian counterparts Monday in Russia's Sochi sea resort as part of ongoing cooperation among the countries over resolving the Syrian civil war.
"We can go our own way," Turkish media Sunday quoted President Recep Tayyip Erdogan as saying. "The U.S. could lose a loyal and valuable ally," he added in response to U.S. threats.
In the past week, Turkish-U.S. tensions have rapidly escalated with President Donald Trump warning of "severe sanctions" if Turkey does not release an American pastor, Andrew Brunson, from detention.
Brunson is under house arrest on terrorism charges which Washington has dismissed as "baseless." Ankara says the issue is a matter for the courts.
Meanwhile, Russia is successfully courting Turkey.
"This is the coziest relations have been in the [Turkish] republic's history," said former senior Turkish diplomat Aydin Selcen, who served in Washington and Middle East. The two countries have rapidly deepened relations in cooperation over the Syrian civil war and trade.
Turkey's decision to purchase S-400 missiles from Russia is exacerbating concerns among Ankara's Western allies, with Washington warning the missiles threaten to compromise NATO defense systems. Turkey and the U.S. are NATO allies.
Analysts suggest Washington's increasingly hard-line approach toward Ankara over the Brunson case can in part be explained by broader concerns about Turkey's allegiance to its Western allies. Trump's threat of sanctions could be an opportunity for Russia's President Vladimir Putin.
"I wouldn't rule out Putin selling Erdogan some sort of insurance policy against American wrath," political analyst Atilla Yesilada of Global Source Partners said. "But Putin has everything that Turkey needs, except money. And Turkey is in desperate need of foreign funding. Only the West can provide those loans."
The U.S. Congress, aware of the Turkish economy's heavy dependence on overseas borrowing, is threatening measures to restrict Turkey's ability to borrow money.
Experts also question whether it is in Putin's interest to further deepen relations with Ankara.
"I don't think Moscow wants Turkey closer than this," Selcen said. "It's enough for them to play their game to keep NATO weak, to keep Turkey with one foot in the West and one foot in the East because it's not in President Putin's interest to have Turkey dependent like Belarus. Let's remember the Russian economy is smaller than California. Russia can't carry Turkey's burden. It can't even carry Syria."
Turkey and Russia are historically regional rivals.
"Turkey has always balanced its relations between West and East," says international relations professor Huseyin Bagci of Ankara's Middle East Technical University. "Turkey knows the limitation of cooperation with Russia."
Syria a catalyst
An Erdogan adviser, speaking on condition of anonymity, last month stressed Ankara remained committed to its Western alliances and relations with Russia are based on the necessity of resolving the Syrian civil war and trade.
Ankara's cooperation with Moscow over Syria faces growing strains. Turkish officials accuse Russia of reneging on an agreement to create de-escalation zones where a cease-fire would protect Syrian rebels. The zones were established as part of the "Astana Process" in which Iran, Turkey, and Russia cooperate to resolve the Syrian war.
Much to Ankara's anger, Syrian regime forces backed by Russian airpower are gradually overrunning the de-escalation zones. Erdogan has vowed to protect the last main zone in Idlib, on Turkey's border. Monday's Sochi meeting of Turkish, Iranian and Russian officials is expected to focus on the future of the Idlib enclave.
The Helsinki summit between Putin and Trump earlier in July could further strain Turkish-Russian ties.
"In Helsinki, there was a four-hour meeting. There was substance; there appears already the grounds of a final political agreement over Syria," former Turkish diplomat Selcen said.
"President Trump is, more than President [Barack] Obama, ready to hand over Syria to President [Bashar] Assad, once IS is defeated," Selcen said. He said it shows that "Moscow and [the] U.S. can agree on Syria, which could mean Turkey can be frozen out, as Turkey cannot resist Moscow and [Washington] DC over Syria."