A heavy artillery barrage on the Ukrainian port city of Mariupol in late January killed around 30 people. At the time, NATO commanders thought the strike presaged a new offensive into the city, but a concerted attack never materialised.
Russian regular forces continue to occupy staging positions on the borders of south-eastern Ukraine, but neither the Russian-allied separatists nor the Russian military appear to be willing to escalate the crisis. The region is in the middle of northern hemisphere winter, so until the spring arrives heavy fighting will be difficult to conduct.
However, NATO has long suspected that Russian troops are in position to secure a land corridor between Russia and the Crimean Peninsula. Whether the rebels currently possess the capability to take and hold this corridor is unknown. But Russia has been moving regular forces, including some elite units, into nearby Donbas for months.
A strike towards Crimea would be possible, and likely successful, should the rebels choose to take it. The timing would have to be exactly right, because it is a long drive through a mostly hostile countryside which would stretch supply lines.
Russia could sell the move with a narrative meant to “assist” Russian-speaking “citizens” in Eastern Ukraine. But it would be a significant escalation of the conflict, which has been confined to low-level border skirmishes.
NATO commanders have probably thought about the possible moves Russia can make in Ukraine and know how truly weak Moscow’s long-term hand is.
The US and the European Union have chosen the sanctions and humanitarian aid pathway to counter Russian bellicosity, but have conspicuously – to the frustration of many – refrained from assisting Ukraine with military aid.
Yet all that could be changing with the announcement on Tuesday that NATO’s military commander Gen. Philip Breedlove now supports providing defensive weapons and equipment to Kiev’s forces operating against the rebels.
President Barack Obama has made no decisions on providing lethal assistance, but Secretary of State John Kerry will visit Kiev this week and is reportedly open to discussing the idea. National security advisor Susan Rice is also “prepared to reconsider the issue”.
The United States is not about to send a Marine Expeditionary Unit into eastern Ukraine, neither is NATO likely to reposition troops to confront Russian regular forces. Weapons will only bolster the Ukrainian military, say White House advisers.
However a cost-benefit analysis suggests the decision is all about timing and semiotics. The fog of war complicates the ability to understand an enemy’s movements, but it also obscures one’s own signals making it difficult to ensure the message is read correctly by the other side.
In announcing lethal aid, NATO is trying to create a situation in Ukraine in which the Kremlin considers the option of further military action in or against Ukraine too costly to pursue.
The end game is to force Moscow to hesitate too many times while Kiev and NATO use the openings to buttress Ukrainian positions, which will result in further hesitation and hopefully force Moscow to negotiate a genuine settlement. NATO commanders suspect that Russia is already taking advantage of the situation further than it originally planned.
Yet the question is not whether the arrival of lethal aid change the military calculus - it almost certainly will. The question is whether that endgame can be reached simply by bolstering Ukrainian defence. That part is improbably at best.
First, it is unclear whether Russia truly desires peace in eastern Ukraine as this would essentially revert the country onto its original path of becoming pro-Western. Second, the delivery of military aid sends the signal that this is as far as NATO and the US are willing to go in defending Ukraine.
Whether that second factor is true or not is exactly what Moscow will see. Supplying just enough lethal aid to Ukraine may deter Russia from launching a new offensive to counter the new weapons, but how much aid is “just enough” exactly? And how much deterrence would 40,000 Russian troops and aircraft need to stand down?
Couching the weapons delivery as NATO-supplied paints the decision as multilateral. But should other US allies such as Canada or Britain not assist, then it will begin look very much like the United States is fighting Russia via Ukrainian proxies. So after all this time, Mr Putin’s claim that the US is behind all anti-Russia movements in Ukraine will be hard to counter.
Lethal aid without US military assurance is bound to make the Baltics and Poland nervous too. Because if Russia thinks it can get away with securing a corridor from Mariupol to Crimea while the new weapons take six to eight months to arrive - and the NATO certainly won’t intervene - might it take the chance?