A Ship Was Sunk Off The Bulgarian Coast. Sofia Summoned The Russian Ambassador.

Bulgaria summoned the Russian ambassador to the country after vessel was sunk by a drone off its coast, with 11 sailors missing as a result.

And while authorities stopped short of directly accusing Moscow of being behind the attack, Prime Minister Rumen Radev said it "benefits the Russian Federation".

"This is absolutely unacceptable: another attack in the immediate vicinity of Bulgarian territorial waters," Radev added in a televised address.

Ukrainian Foreign Minister Andrii Sybiha did blame Russia, saying the strike "once again demonstrates Moscow's deliberate disregard for civilian lives".

"We urge our partners to step up pressure on Russia, strengthen sanctions, and take decisive action to hold it accountable and protect freedom of navigation," Sybiha added.

Several European countries have warned that Russia is escalating hybrid attacks in the continent.

The Danish Defence Intelligence Service released a report in September noting that Russia has "intensified its use of sabotage, destructive cyber attacks and is attacking targets in Europe with drones," concluding that "hybrid war is escalating."

It went on to recall a foiled drone attack in Germany, which Berlin openly blamed on Moscow, noting that it has "become more willing to take risks." And warned of potential "sabotage on Danish soil against defence companies."

Elsewhere in the report, the agency noted that Russia is "under more pressure than it has been at any other point during the war against Ukraine," sustaining heavy losses on the battlefield and with the economy "on the brink of a major crisis."

The document then notes that Russia has no prospect of "achieving any major breakthroughs in the war against Ukraine over the next six months," and it's unlikely that President Vladimir Putin will "be willing to compromise on his fundamental objectives of war."

In this context, Russia warned that is ready to use nuclear weapons if NATO seeks to cut off Kaliningrad, a Russian exclave on the Baltic Sea that has been at the center of renewed tensions between Moscow and the trans-Atlantic alliance.

A document from Moscow accuses the alliance of going through a "dangerous and reckless course" that puts the sides at "high risks of the outbreak of a direct armed conflict," according to Reuters. It also threats with "Russian strikes against decision-making centers in the alliance's member states right from the outset".

"Russia will be ready to use the entire arsenal of forces and capabilities at its disposal, including nuclear weapons, in order to defend its territory should NATO countries undertake any attempt aimed at isolating the Kaliningrad Region from the ​rest of the country," the document added.

NATO Secretary General Mark Rutte reacted to the message, saying "we are a defensive alliance" and called on Moscow to "stop the nuclear threats." "This is absolutely not called for and not helpful," he added.