One wouldn't know it by looking at the market, but the biggest developing story today was Russia's threat to intercept any aircraft - including US - flying in the area of operations of the Russian Aerospace Forces in Syria, and "be followed as targets" after yesterday's downing by a US F-18 of a Syrian Su-22 fighter jet. Moments ago the US responded to this unmistakable deterioration in relations between the two nations, when a Pentagon spokesman said U.S. pilots over Syria will defend themselves if attacked by Russians.

"We are aware of the Russian statements," Navy Capt. Jeff Davis, a Pentagon spokesman, said Monday morning quoted by WashEx. "We do not seek conflict with any party in Syria other than ISIS, but we will not hesitate to defend ourselves or our partners if threatened," Davis said, seemingly unaware that shooting down a sovereign nation's plane above its own territory is exactly what "seeking a conflict" looks like. In a follow up statement this afternoon, White House spokesman Sean Spicer said the US will "retain the right of self-defense in Syria."

Separately, Col. Ryan Dillon, chief U.S. military spokesman in Baghdad said "coalition aircraft continue to conduct operations throughout Syria, targeting ISIS forces and providing air support for coalition partner forces on the ground."

Unlike Davis, Dillon appeared to indicate the U.S. will avoid the parts of Syria where Russia said U.S. planes would be tracked as potential targets or providing additional airpower to counter threats.

"As a result of recent encounters involving pro-Syrian regime and Russian forces, we have taken prudent measures to reposition aircraft over Syria so as to continue targeting ISIS forces while ensuring the safety of our aircrews given known threats in the battlespace," Dillon said. He added that coalition aircraft will continue operations against Islamic State targets “while ensuring the safety of our aircrew given known threats in the battlespace,” he said.

"I'm sure that because of this neither the U.S. nor anyone else will take any actions to threaten our aircraft," he said, according to state-owned RIA Novosti news agency. "That's why there's no threat of direct confrontation between Russia and American aircraft."

Earlier, the Russian defense ministry called the US attack on a Syrian jet “a cynical violation of Syria’s sovereignty” and said Russia was halting so-called deconfliction coordination with the U.S. aimed at averting air incidents.

Menawhile, Russia doubled down after Viktor Ozerov, the Russian parliament's, defense committee’s chairman, said U.S.-led aircraft in Syria may face “destruction” if they threaten the lives of Russian pilot. While Russia hopes it won’t have to take such action, “we won’t allow anyone to do what happened to the Syrian plane to our pilots,” he said.

Frants Klintsevich, deputy head of the defense committee in Russia’s upper house of parliament, said the the Defense Ministry’s response doesn’t mean there’ll be war with the U.S., though it’s a “pretty serious” signal that Russia won’t accept acts of aggression against Syria.

On the other hand, “lawmakers have no influence” on the Kremlin’s policy toward Syria and “all Russian actions, not rhetoric, show that Putin is trying now to avoid escalation with the West,” said Ruslan Pukhov, head of the Center of Analysis of Strategies and Technologies in Moscow. To be sure, Russia previously vowed to halt deconfliction coordination in April, after the U.S. bombed a Syrian airbase in response to the alleged use of chemical weapons by Assad’s forces. But the U.S.-Russian communications to avoid clashes in the skies over Syria resumed after only a few days.

Whether relations between the US and Russia normalize in the coming days, however, suddenly the Middle-east is a far more dangerous place even without this latest escalation, following not only the Qatar crisis, but the just reported alleged terrorist attempt by Iranian Revolutionary Guard Corps on an offshore Saudi oil field. As such, avoiding the spark that launches the next conflict is becoming increasingly more difficult.