Ukraine could be nuclear flashpoint

US paratroopers will train Ukrainian troops as part of Operation Fearless Guardian. Photo / AP

The risk of a US-Russian war is at its highest since the Cuban missile crisis, raising fears that it might lead to the unthinkable

This week's announcement by the Pentagon that 300 US paratroopers from the 173rd Airborne Brigade had arrived in Lviv to help train Ukrainian national guard units met with a predictable response from the Kremlin.

The US decision, which follows a British deployment of 75 soldiers for the same purpose in February, "could seriously destabilise the situation in Ukraine", said Kremlin spokesman Dmity Peskov. The arrival of the 173rd Airborne, he said, would not help resolve the conflict.

The fight between Ukraine and Russian-backed separatists has killed at least 6116 people as of last week, according to the UN, and heightened Russian-Nato tensions.

The 173rd's deployment arguably violates the February Minsk ceasefire, whereby all foreign forces quit Ukraine. In fact, it is realpolitik, a response to barely disguised Russian military support to the separatists.

The paratroopers will remain for at least six months, training 900 Ukrainian national guardsmen in infantry tactics as part of Operation Fearless Guardian, according to the Pentagon. It is the latest of several US deployments, now backed by fellow Nato member Canada. Last week, Anders Fogh Rasmussen, Nato's ex-Secretary-General, said: "We are pretty close to a new Cold War because of Russia's illegal actions in the Ukraine."

In some lights the 173rd and other Nato deployments are a slippery slope as continuing violence, most recently at Shyrokyne, violates the ceasefire. Doves fear Vietnam-style "mission creep", where initial deployments suck in ever more troops, escalate tensions and heighten risk of a wider war.

The Obama Administration has sought to carefully calibrate its response, mixing sanctions - this week Russian Prime Minister Dmitry Medvedev said existing sanctions will cost US$106 billion ($140 billion) - with army trainers and, from this month, US$75 million in "non-lethal" material, such as Humvees.

The big unknown is if Putin will - and can - succumb to pressure. To some extent he finds himself in a corner; hammered by sanctions, a falling ruble and plummeting oil prices and hoisted by his own nationalistic petard, in which the US and Nato poach Russia's traditional sphere of influence. At a marathon four-hour annual call-in show with Russians last week, Putin accused the US of treating other world powers as "vassal states".

The crisis also points to the West's failure to integrate Russia into Europe, although, given Moscow's authoritarian and kleptocratic character, this may have always been too much to hope for.

"My take is that Russia is set on the path of conflict escalation," says Pavel Baev, Russia expert and senior nonresident fellow at the Brookings Institute. "The room for political manoeuvring is limited not by Western policies, but by the deepening economic crisis in Russia. Every measure that makes the next step in escalating the hostilities more difficult and expensive for Moscow is a step in the right direction."

Doves believe a "new detente" is necessary if a new Cold War, without the safeguards of the old one, is to be averted. This involves some kind of US-Russian parity, wiped out by triumphant American claims it had "won" the Cold War, leaving the US as the world's "indispensable nation".

The crisis - which began when Russia annexed the Crimea in March last year and intensified as separatists seized parts of eastern Ukraine - has revived Cold War-style brinkmanship.

The European Leadership Network cites multiple near-misses between warplanes, airspace violations, emergency scrambles, close maritime calls and simulated Russian bombing attacks on the West. Could a skirmish between pro-West and pro-Russian fighters in Ukraine spiral into a wider conflict involving heavy weapons, tactical nuclear weapons and then - the nightmare scenario - strategic nuclear strikes?

During the Cold War mutually assured destruction - MAD - by nuclear weapons was a deterrent. After the Cuban Crisis President Kennedy warned the US must always avoid leaving an enemy with a stark choice between "humiliating retreat or a nuclear war". Moscow is keen to avoid humiliation in Ukraine. Its military planners have said nuclear weapons might even be used against a conventional attack. And Putin was quite open that he would use nukes to hold on to the Crimea.

A Ukrainian soldier guards OSCE observers. Photo / AP

With hawks like Senator John McCain calling the ceasefire a failure, and demanding US arms shipments to Ukraine, Stephen Cohen, professor emeritus of Russian studies, history and politics at New York University, warns the risk of a US-Russian war is at its highest since the 1962 Cuban Missile Crisis. The Bulletin of Atomic Scientists has moved its Doomsday Clock, a barometer of nuclear tensions, forward to three minutes from midnight. As US-Russian nuclear arms reduction talks are frozen, a new cruise missile, the Iskander, capable of delivering a nuclear warhead, has reportedly been deployed to Kaliningrad, the Russian Baltic enclave. Asked if they could deploy nukes in Ukraine, Russia said, yes, "in principle". No one is sure if surrendering to Russia - letting "aggression go unchecked" in British PM David Cameron's words - will embolden the Kremlin and provoke more land grabs of former Soviet satellite states. Hawks, who draw parallels with Nazi revanchism in the 1930s, cite Russia's 2008 invasion of Georgia. Putin is testing Western resolve. Sending in Nato trainers will force him to back down. Doves argue that Russia feels encircled and fears US subjugation. Military escalation, they say, will stiffen Russia's resolve.

This week The National Interest, a conservative US magazine, argued the US and Russia are "stumbling towards war". The West has yet to formulate a clear Ukraine policy. "On the battlefield of war in Ukraine, Russia has what Cold War strategists named 'escalation dominance': the upper hand at every step up the escalation ladder," it said. "This is a proxy war the United States cannot win and Russia cannot lose - unless America is willing to go to war itself."

Given the nuclear threat, that seems unthinkable. Yet, the possibility that a regional war might spiral beyond control remains a real risk.