A highly sophisticated US Navy P-8A Poseidon maritime patrol plane, also known as a "submarine killer" was observed by the Strategic Sentinel flying south of Cyprus, having likely departed from Naval Air Station Sigonella in Italy, and headed eastward toward Syria on Tuesday.

1744z: PS246 has set up an orbit at 9,500 feet just West of Tartus, Syria. pic.twitter.com/D34i2nWhTN — Aircraft Spots (@AircraftSpots) April 11, 2018

The flight comes at a time when not a single commercial plane can be observed over Syria, as per the guidance of Europe's Air traffic control which last night warned that airstrikes on Syria are imminent.

A recent flight path history shows the Poseidon engaged in heavy shore "sniffing" designed to uncover whether any Russian subs are hiding near Syria.

Below we present some more details on the P-8 Poseidon Submarine Killer courtesy of The National Interest.

There is a decent chance you have already flown on one of the U.S. Navy’s key new aircraft—or rather, the 737 airliner it is based on. The P-8A Poseidon maritime patrol plane may not be as sexy as an F-35 stealth fighter, but in some ways it is far closer to the forefront of international flashpoints in the Pacific Ocean. Maritime patrol planes are essential for tracking the movement of ships and especially submarines across vast oceanic waters—and potentially sinking them in the event of hostilities.

Hunting submarines from the air, however, is an airpower-intensive job that requires numerous airframes spending thousands of flight hours flying long-distance patrol patterns over the ocean. Since 1962, the U.S. Navy has operated the P-3 Orion patrol plane, based on the four-engine L-88 Electra airliner. The turboprop-powered aircraft could spend a dozen hours flying low over the ocean to drop sonar buoys, scan the water for metallic hulls of submarines with its Magnetic Anomaly Detector (MAD) and potentially launch torpedoes. After fifty-five years of able service, however, the P-3s have accumulated thousands of service hours and their hulls are growing fatigued.

In 2004 the U.S. Navy selected the jet-powered Boeing P-8 Poseidon to succeed the aging P-3. Development proceeded relatively smoothly, in part due to the use of a preexisting airframe and the decision to phase in the P-8’s advanced systems in a series of increments rather than delivering them all at once. This led the P-8 unit costs to actually come in under budget, at $150 million per aircraft.

The P-8 is based on the 737-800ERX short-to-medium-range airliner. It typically has a flight crew of three and boosts stronger power generators for its onboard electronics. The Poseidon reportedly offers a much smoother ride than the Orion, thanks to its broader-swept wings and flight computers. Orion crews were often nauseated by the strong turbulence their low-altitude flight operations required.

The Poseidon’s primary payload is its diverse array of sensors. These include an APY-10 multi-mode synthetic aperture radar, which not only can track the position of ships over hundreds of miles away, but possesses a high-resolution mode which can spot submarine periscopes poking above the waves and even identify different classes of ships. An MX-20 electro-optical/infrared turret provides a shorter-range search option, while an ALQ-240 Electronic Support Measure (ESM) derived from a system onboard the EA-18G Growler functions as an electromagnetic sensor, particularly useful in tracking the positions of radar emitters.

A recent addition is the Advanced Airborne Sensor, a dual-sided AESA radar that can offer 360-degree scanning on targets on land or coastal areas, and which has potential applications as a jamming or even cyberwarfare platform.

A number of key systems on the P-8 are designed to track submerged submarines. A rotary launcher system in the rear of the P-8 can dispense sonar buoys into the water. A recent upgrade allows P-8s to employ new Multistatic Active Coherent buoys that generate multiple sonar pulses over time, allowing for greater endurance and search range. The P-8 also has its own acoustic sensor, and even a new hydrocarbon sensor that can “sniff” for fuel vapor from submarines.

However, the P-8 lacks the tail-mounted MAD sensor of the P-3 Orion, useful for detecting the metallic hulls of submarines while flying at low altitude. Various reasons have been offered for its removal: the MAD weighed too much at 3,500 pounds, it did not fit with the high-altitude search profile of the P-8, or the new sensors on the P-8 rendered it unnecessary. However, the U.S. Navy is reportedly developing a variant of the an air launched drone, called the High-Altitude Unmanned Targeting Air System, which can carry a MAD sensor and transmit its findings back up to the P-8.

Five operator stations on the port side of the plane carry multifunction displays that can be configured to display whatever sensors and controls are most useful under the circumstances. The P-8’s computers are designed to fuse the data into a single coherent picture for the operators—and can then “push” that data to friendly ships and airplanes. This is a capability the U.S. Air Force has been struggling to integrate into its new E-3G radar planes. The P-3 is also designed to be especially compatible with Navy RQ-4N drones.

In the event of hostilities, the Poseidon can carry five missiles, depth charges or torpedoes in a rotary launcher in the rear hull, and six more on underwing racks. While the P-3 had to fly low to deploy its torpedoes, the P-8 can use a special High Altitude Air Launch Accessory to transform its Mark 54 324-millimeter lightweight torpedoes into GPS-guided glide bombs that can be dropped from altitudes as high as thirty thousand feet. These shed their wings upon hitting the water and hone in on targets using onboard sonar. Poseidons can also carry Harpoon AGM-184H/K antiship missiles with a range of 150 miles.

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The Poseidon entered service with the U.S. Navy’s VP-16 squadron at Kadena Air Base on Okinawa in 2013, and around fifty out of a planned 117 are now operational in U.S. service.

The type’s patrol duties have placed it at the forefront of political disputes between the United States, China and Russia.

It was already a long-established and accepted custom for countries to intercept each other’s patrol planes over international airspace. However, this becomes risky when intercepting fighters perform unsafe maneuvers as part of their efforts to intimidate the observation planes. Such antics led to a collision between a Chinese fighter and an EP-3 observation plane in 2002 with fatal results for the Chinese pilot.

On May 9, 2017, a Russian Su-27 fighter buzzed within twenty feet of a Poseidon that was patrolling the Black Sea. The P-8s in turn have practiced chasing Russian submarines. According to the Aviationist, in December 2016 Poseidons were engaged in hunting one or two carrier-hunting Oscar-class submarines in the Mediterranean. Maritime patrol aircraft are one of the few weapon systems that can routinely practice hunting their adversaries under operational conditions—stopping just short of releasing weapons, of course.