November 13, 2016

Russian Kilo subs and seabed sensors involved in 2 NATO submarines' detection

This depth-map indicates the choke-points (narrows) where both NATO submarines entered the Mediterranean Sea, ie. the US Virginia class through the Strait of Gibralter (on the map, extreme left) and the Dutch Walrus class (lower, right corner) near Port Said, Egypt.


Various Russian sensors were involved in the recent detection of two NATO submarines. Sensors included:

-  publically admitted, over-water (ASW helicopters) and surface ASW ships (see BACKGROUND)

-  (more secretly) Russian Kilo submarines, near stopped, operating at choke-points. 

-  equally secret were seafloor sensor arrays used: near the Strait of Gibraltar; another north of Port
   Said at the northern opening of the Suez Canal; and yet another outside of Russia's Tartus (Syria)

Russia's Main (Military) Intelligence Directorate (known as GRU) reported that a Dutch Walrus class submarine transiting the Suez Canal emerged into the Mediterranean Sea only to "rendezvous" with, be intercepted by, various ASW sensors.

GRU was already aware that the Dutch sub, after Indian Ocean regional ops, had then transited the  Suez Canal from south to north with a known time of emerging into the Med. This made it quite easy for a Kilo (from the Black Sea fleet) to cue or "rendezvous" with the Dutch sub. This Kilo gained valuable intelligence on characteristics of some upgrade work done on the Dutch sub.

The US Virginia class SSN had earlier been (predictably) tailing the Admiral Kuznetsov carrier group from a range of 70km. As the Virginia class sub transited the Strait of Gibraltar (traveling from west to east into the Med) it was detected by a fixed seabed sensor array (perhaps in cooperation with local assistance). The detection was later confirmed by Russian helicopter dipping sonars (active) and ship bow sonars.

GRU further reported that, by their behaviour, the Walrus and Virginia class subs positively detected the presence of the Kilo subs.


Allen Cone, for UPI reported on 9 November 2016 "Russia: Dutch sub tried to approach, spy on aircraft carrier"

"(MOSCOW, Nov. 9 (UPI)) -- A Dutch submarine attempted to spy on a Russian aircraft carrier after approaching it in the eastern Mediterranean Sea, a Russian Defense Ministry spokesman said Wednesday.

The Northern Fleet's anti-submarine ships forced the sub to leave the area near Russia's Admiral Kuznetsov aircraft carrier, spokesman Maj. Gen. Igor Konashenkov said in a statement.

"The clumsy attempts to carry out dangeroumanoeuvres in the direct proximity of the Russian group of warships could have led to grave navigation consequences," he said.

He said two anti-submarine ships, Severomorsk and the Vice-Admiral Kulakov, at 6:50 a.m. spotted a Dutch navy sub, which neared the Northern Fleet's aircraft carrier group for surveillance purposes."

He said the crews "easily identified the submarine that was 20 kilometers [12.5 miles] away using the standard onboard hydroacoustics systems and data obtained from anti-submarine helicopters Ka-27 PL. Despite the submarine's attempts to evade surveillance, a stable hydroacoustic contact was established with it."

Konashenkov said they monitored the submarine for more than an hour and forced it to leave the carrier group.

"It is noteworthy that submarines of such class, having big displacement, are not fit for reconnaissance," the spokesman said.

The ministry official also said the Russian navy's aircraft carrier group regularly spotted NATO's submarines on its way to the Mediterranean.

Earlier this month, he said the USS Virginia was trying to spy on Russian vessels.

Last month, Russia's Northern Fleet's the Kuznetsov aircraft carrier, accompanied by the Pyotr Veliky battle cruiser, the Severomorsk and Kulakov, and support vessel were sent to the Mediterranean to hold drills and strengthen capabilities."

Please connect with Submarine Matters articles:

-  Russia set to unleash carrier aircraft and SLCMs on IS in Syria of  31 October 2016, and 

-  Russian carrier Admiral Kuznetsov may conduct first airstrikes (against IS), October 17, 2016.



AncientSubHunter said...

So, Pete...what do you know about the "seabed" sensors? How are they monitored? Real-time or delayed.

I'm having a hard time understanding (from a SOSUS context), how the Russians are able to place sensors at the Strait of Gibraltar.

Peter Coates said...

Real-time, few seconds delay, via satellite feed, to Moscow.

Otherwise all is NTK.

Peter Coates said...

Little over 270 milliseconds to Москва. Den weez think about it, cobber.

Josh said...

What is your source for there being a permanent Russian sensor in the straight of Gibraltar? I'd be surprised if such existed; I can't imagine the Moroccans being so friendly such as to host a permanent Russian listening post. I could however imagine that an escorting Akula could steak out the straight ahead of time, or alternatively one of the escorting Udaloys could simply actively ping the area to detect trailing subs. Subs forced to move through a choke point at a particular time and speed (ie, high speed transit while trailing) are going to be at a severe disadvantage for any sensor type.


Tim Boxall said...

G'day Pete,
The 2 reports are contradictory in nature and facts. GRU said: "The crews easily identified the submarine that 20 kilometers [12.5 miles] away using the standard onboard hydroacoustics systems and data obtained from anti-submarine helicopter Ka-27 PL."
I'm also confused by the mention of "seabed sensors" picking up something like Walrus and the need to even have them (if they exist at all) at the Strait of Gibraltar.
Of course Russia were aware of NATO submarines transiting the Suez Canal. They are on the surface. Can't go through at PD.

Peter Coates said...

Hi Tim

You've forced me to have another look at the Chinese NSA bug output of the GRU conference room in Moscow (Did I mention the Chinese connection? Please keep this to yourself, comrade!).

The Chinese output reveals Russia used several, non-contradictory, detection methods - some admitted (like ASW helicopters) and some not admitted (like seabed arrays "SOSUS"). As readers of Submarine Matters will note SeaWeb sensor platforms work together in a network rather than individually see .

The US/West has its SeaWeb and Russia has its own more limited SeaWeb. However Russian penetration - GRU and SVR payoffs to several third-country Western SeaWeb operators - permits unintended beneficiary "piggybacking".

The Walrus class sub being on the surface (that you've advised) in the Suez canal made the Kilo "rendezvous" (interception of the Walrus) all the more simple. That Russian sensor array, that is north of Port Said, is just a highly SECRET (you didn't read this) backup portion of the Russian SeaWeb network.

Please note Russia's and Egypts heritage (not entirely lost in some minds) of close alliance. This has been partly rekindled (plus a bit of bribery) by the sales of Russian helicopters to Egypt - see right sidebar at on "Aircraft [Ka helicopters] Carried". This may well have resulted in Russian "piggybacking" on the Western SeaWeb - but I didn't say that.



Peter Coates said...

Hi Josh [at 15/11/16 2:55 AM]

Gentleman don't reveal their sources. Silence generally involves $$ and honour somewhere along the line - and no-one is paying me.

No need for "a permanent Russian sensor in the straight of Gibraltar" Russia is acquiring (piggybacking) the gain from some-one else's? Not Morocco's.

Kilo instead of Akula used because Kilos are quieter. Also 2 other Kilos to avoid need to move noisily.

Just shows how difficult it is to disentangle fact, fiction and secrecy :)



Josh said...


There's no way a Kilo came down with the Kuz group; it couldn't hope to keep up. Perhaps one was sent from the Black Sea Fleet to meet them at the straight, if anything.


Peter Coates said...

Hi Josh [at 16/11/16 7:19 AM]

Yes Kilo SSK's diesel and battery dynamics mean they would need to run noisily (snorting or on the surface) over a sustained distance so could not keep up discretely-efficiently with the Kuznetsov carrier group.

Russia needs to (would have) prepositioned its Kilo SSK in the Med. Such Kilos would have a near permanent patrol presence in the Med but numbers would escalate in high-requirement times.

The extra Kilos could come from the Black Sea Fleet (as you say) but also the Baltic and Northern fleets.



Josh said...


Kilos operating that far south from the Baltic or North Fleets would be at the edge of their operational range and Russia has no operational submarine tenders to my knowledge, so Black Sea Fleet units seems far more likely.


Peter Coates said...

Hi Josh [17/11/16 3:36 AM]

The Kilos can operate to 7,500 nautical miles on snorkel and probably further on the frequent transit in peacetime mode, which is surfaced. I would say Russian replenishment-oiler ships refueling surfaced Kilos is a goer - see right sidebar at

Once in Med the Kilos (and ships of the Kuznetsov group) refuel at Russia's Naval Base at Tartus, Syria.



Josh said...


Continuous snort is probably not the most efficient long distance mode. I suspect quickest transit mode is cruising underwater where the hydrodynamics of the boat are optimized. I also wonder if it isn't more efficient to run on battery at speed since I structural stress put on the snorkel might limit the speed the boat can snort on (what is the top speed a mast can be raised without bending?). So likely a sprint/drift is the fastest rate of advance, or minimally remaining submerged which favors the hull form.

As to replenishment - the Kilo is a coastal type and its needs would go well beyond simple diesel fuel. Parts, lubricants, food, possibly fresh water, etc. In an age where every Russian formation deploys with tugs I find it hard to believe a Kilo would self deploy that far out of its fleet area with just a civilian tanker to support it, but perhaps the Russians have some arrangement for this.


Anonymous said...


3 things

1. You cant dive in the Suez Canal

2. Walrus was seen by the Russians at Malta a couple of days before, there is a resupply base there.

3. On the same day the Russians let this news out there was a parliament hearing about the subs and the navy can not tell anything about the sub activities this includes the MP`s. The Navy spokesperson was made mute by this news outlet in the Dutch parliament.


Peter Coates said...

Hi Kevin

Thanks for the information - especially:

2. about the submarine resupply at Malta. This predictable stopping point for SSKs would benefit the Russian Navy's pursuit and shadowing efforts.

Looks like surface ship visits to Malta are logged but maybe not subs

Here's snippet on a 2010 visit of a Dutch sub to Malta's Grand Harbour

3. Yes parliaments don't like to place submarine movements on their officials records-minutes