In light of the escalation taking place in Idlib, Syria, and the possibility of a confrontation between the Turkish and Russian armies in Syria, flight data and ship traffic control showed that Russia is accelerating the pace to reinforce its forces in Syria by sea and air before talks between Presidents Putin and Erdogan in Moscow on Thursday.
Presidents Vladimir Putin and Recep Tayyip Erdogan agreed to meet after escalating tensions between their two countries as a result of the fighting in Idlib between the Russian-backed regime forces and Turkey's mercenary groups.
According to observers, this incident raised concern in Moscow that Turkey could close the Bosphorus Strait to Russian warships and prevent Russian military transport aircraft from using Turkish airspace.
The Russian Ministry of Defense has yet to comment on this information, and a Turkish official, who did not want to be named, said that there is no plan to close the strait, which will force Russia to take longer routes to Syria.
But Russia appears to be working to reinforce its presence in Syria at its fastest rate since October, when US forces withdrew from parts of Syria and Moscow rushed to fill the void.
Reuters monitoring of the Bosphorus since February 28 shows that Russia has sent five warships to Syria within six days, exceeding the usual limit of sending one or two warships a week.
Turkey responded by strengthening the protocol for escorting Russian warships that use the Bosphorus Strait, as it accompanied three Turkish patrol ships and a Russian frigate helicopter, while such ships usually sail along with one coast guard ship.
Flight data showed that at least five passenger and cargo planes operated by the Russian army had reached Syria, including three on a single day since February 28.
This came in the wake of the arrival of 12 other military aircraft within 18 days. This marks the largest Russian military air activity in Syria since October.
Publicly available tracking data provide only a glimpse into Russian military flights to Syria because not all of these aircraft can be tracked.
One of the people working closely with Russian forces in Syria told Reuters that Moscow's efforts were to send a message to Ankara and "show muscle."
The person added that the swift buildup is a guarantee card in the event that the Putin and Erdogan meeting fail, and Ankara imposed restrictions on the Bosphorus Strait or its airspace.
Turkey is showing signs that it has detected Russian reinforcements of its forces near Hmeimim, its main air base in Latakia province.
"Russia is conducting major reinforcements near Hmeimim," a Turkish security official said, adding that Moscow had stepped up logistical support for the regime's forces.
"These are moves that might harm the positive atmosphere that may prevail tomorrow's meeting," he added, but he expressed hope for "positive results."