The Fine Line the US Is Straddling In Providing Defensive Support to Ukraine

As Ukrainian military forces and civilians continue to get pummeled by pro-Russia rebels on the front lines in eastern Ukraine, the US has committed to aid Ukraine by providing new military systems. Late last year, the US sent the first wave of advanced anti-mortar radar systems, along with some trainers, to support Ukraine in its current conflict.

Artillery and mortars have historically accounted for the majority of battlefield casualties, and both remain grim favorites of both sides of the Ukrainian conflict, even as their limited accuracy have contributed to innocent civilian deaths and injuries.

In November, the US committed $118 million in aid to help Ukraine's security forces in response to Ukrainian President Petro Poroshenko's formal request July 7 for non-lethal aid from the international community in order to "ensure the ceasefire and contain the aggression." The aid money is also separate from $2 billion of loan guarantees the US committed to Ukraine in January 2014 to help stabilize its economy.

The first three of 20 promised AN/TPQ-49 lightweight counter-mortar radars (illustrating the Army's knack for snappy nomenclature) arrived in Ukraine along with Vice President Joe Biden on November 21. The system is designed to be mobile and set up by two people in under 20 minutes, but it must be converted to work with the European power grid — just like using a clunky adapter to charge your phone overseas.

The first US Army training team included two technicians from Tobyhanna Army Depot in Pennsylvania, who trained Ukrainian military officers on how to operate, set up, and troubleshoots the radar. Although the US Army sent medics to train the Ukrainians in November, this is the first time the US has specifically sent trainers for a weapons system.

Related: Ukraine ceasefire ignored as fierce battle for Debaltseve continues to rage. Read more here.

But what exactly is this mysterious anti-mortar radar? It's a system that can detect and track incoming mortar rounds, from up to three miles away.

The system uses a radar, about the size of a refrigerator, to locate an incoming fast-moving object, such as a mortar-round. After it has located the incoming round a couple of times in a row, the system makes a "track" — meaning that the system has enough information to predict the speed and location of the round. Because mortar rounds, artillery shells, and simple rockets don't have a fancy steering mechanism on them which would give them an unpredictable trajectory, once the system is tracking the round it can rewind that information to about where it was fired in the first place, or fast forward it to see where it's going.

A disadvantage of this system — and what separates it from many of the gunfire locator systems used in major US cities — is that it actively emits a radar signal. Where gunfire locator systems use passive acoustic sensors to pinpoint where shots were fired from, this system emits a distinct radar signal. This signal allows the anti-mortar radar to have more precise tracking of rounds, but also allows eastern Ukraine's rebels to track where the systems are — as long as they have the right type of radar detector.

This system straddles a fine line between providing defensive support to the Ukrainians, and giving them offensive military weaponry to fight pro-Russia forces. This is due, in part, to the fact that this system is all about providing information, and information doesn't break down neatly into "defensive" and "offensive" categories.

For instance, the anti-mortar radar is able to detect where the mortars are coming from, provide early warning of incoming rounds to troops on the ground — but it can't actually fire anything back, which would make it a defensive system, right?

So far, the US hasn't committed to providing the follow-up pieces of the system that actually destroy the incoming rounds. The natural follow on would be a Counter-Rocket Artillery and Mortar (C-RAM) system like the US-backed Israeli Iron Dome. C-RAM systems fire a bullet or missile at a projectile to intercept and destroy incoming rounds, but they usually don't have the capability to fire offensively at a ground-based target. Which still seems to be a pretty defensive application.

On the other hand, Ukrainian forces can also send information from the system to their own mortar or artillery pieces, to cue up a reactive and almost instantaneous artillery barrage at the source of the incoming rounds, which is accurate to within about 250 feet —which would make it an offensive system, right? But the US is leaving the bit about firing back up to the Ukrainian forces —so maybe it's not offensive, then?

Alternately, the system can be used to give ground forces a better battle space situational awareness, or eventually provide detailed information to military leaders to launch an offensive ground attack, or move units out of range of hostile fire. Which is either defensive or offensive, depending on what you do with the information.

US President Barack Obama is still making a decision on whether or not to officially start sending lethal aid to Ukraine, but several key administration officials already support doing so. Biden confirmed that in his statement that the US "will continue to provide Ukraine with security assistance, not to encourage war but to allow Ukraine to defend itself." US Secretary of Defense Ash Carter officially took office on February 17 and made it clear during his confirmation hearings to the Senate that he supports lethal US military aid to the Ukrainian government.

While there hasn't been a detailed list of all the different types of "security assistance" already supplied to Ukraine, in addition to the radar systems, the US has likely already provided non-lethal aid, which the White House has detailed as "body armor, helmets, vehicles, night and thermal vision devices, heavy engineering equipment, advanced radios, patrol boats, rations, tents, counter-mortar radars, uniforms, first aid equipment and supplies."

Ukrainian leaders are calling for additional communications equipment, surveillance equipment to include support drones and other heavy weapons. As of December 18, Obama signed the Ukraine Freedom Support Act, which gives him the authorization to provide lethal aid such as "anti-tank and anti-armor weapons, crew weapons and ammunition" to Ukraine.

Related: Flying Drones with the Dnipro Battalion: Russian Roulette (Dispatch 93)

The start of a training program led by the US military at the Yavariv training center in western Ukraine could pave the way for scaling up US support against the separatist rebels. Every step forward — even on ambiguously "defensive" systems — could be interpreted as a threat from the Russians, and could endanger the delicate peace talks, and what remains of ceasefire agreements.

These systems may still technically fall in the "non-lethal aid" category, but are right on the border of defensive systems and could very easily contribute to offensive operations. As the US and its allies continue to put diplomatic and economic pressure on the pro-Russia rebels, there may be similar shipments of defensive systems that could easily augment offensive operations.