AS UKRAINIAN troops retreat ahead of Russian tanks thinly disguised as separatist rebels, the US is reconsidering military aid. But experts warn: This could lead to full-blown war.

The pro-West Ukrainian government has appealed for “lethal aid” after a ceasefire negotiated late last year was cast aside by pro-Moscow separatists to launch an unexpected midwinter offensive.

The Ukrainian forces are battling to repel waves of militants equipped with modern armour — many still with their Russian unit markings — trying to surround a strategic railway hub in eastern Ukraine.

Ukrainian President Petro Poroshenko has previously appealed to US legislators for military equipment: “One cannot win a war with blankets ... and cannot keep the peace with blankets,” he said.

President Barack Obama has now expressed his willingness to take a fresh look at supplying Ukraine with lethal aid.

It’s a high-stakes move.

“There is a real risk now that we will end up in a war with Russia,” said Fiona Hill, of the Brookings Center in Washington.

“As far as Putin’s concerned we’re already in one, an economic and financial war, and if we start sending in weapons then we’ve taken that up a notch.”

Some military strategists say the recent rebel attacks across key parts of the frontline in eastern Ukraine may have been timed precisely out of fear the United States could soon get involved.

Attack helicopters over #Artemovsk heading for #Debaltseve. 5 streaked low across the road, caught the last #Ukraine pic.twitter.com/zohPHlpJ5n — Maxim Tucker (@MaxRTucker) February 2, 2015

“One reason the rebels have intensified their offensive now is to make gains before potential US arms arrive,” said Andrew Wilson, author of “Ukraine Crisis: What it means for the West.”

“The US faces a moral dilemma: if it does not act now, the conflict could worsen. But there are big risks to getting involved.”

DANGEROUS GAMES

An independent report released last night by eight former senior American officials said it was time for Washington to provide $US3 billion in military assistance to Ukraine.

“The West needs to bolster deterrence in Ukraine by raising the risks and costs to Russia of any renewed major offensive,” the report said.

ICYMI—Here's the full report from top former officials on how the U.S. & NATO should respond to the #UkraineCrisis: http://t.co/ExgACfa36f — Brookings (@BrookingsInst) February 2, 2015

It’s an opinion gaining growing traction among US defence officials and lawmakers.

But it comes with great risk.

“The conflict is being portrayed by the Kremlin as standing up to the West, claiming Kiev is a pawn of NATO,” said Nick de Larrinaga, Europe editor for IHS Jane’s Defence Weekly in London. “Supplying lethal assistance would be fulfilling that prophecy, and could even harden Russia’s position.”

Indeed, part of the rationale for supplying military equipment is that other measures, such as economic sanctions, have failed to deter President Putin.

It’s a view backed by Balazs Jarabik, of the Carnegie Endowment for International Peace: “Western advocates for arming Ukraine have the best intentions, but they are not considering how crazy Russians are about Ukraine,” he said.

The Ukrainian line of defense further collapses – the fall of Nikishyne http://t.co/gDDbAab6Aj (3rd and last mention) pic.twitter.com/dqe4q2WwE1 — Conflict Reporter (@Conflict_Report) February 2, 2015

“They see it as their territory, their people. Their emotional and structural engagement is much greater than it ever will be for the US.”

The fear is that military assistance is only being discussed for lack of other options, and could ratchet up the confrontation to dangerous levels.

“We have to recognise, I’m afraid, that we’re likely to have an increasingly hotter war with more and more devastation,” said Fiona Hillof the Brookings Center in Washington.

“And sending in weapons will only fuel that, and bring in the likelihood that we will have to intervene as well. Just like we had to ultimately in the Balkans and all the other interventions that we’ve done over time.”

OBAMA’S BALANCING ACT

The White House has so far failed to commit, but says it is “constantly reviewing” its strategy.

“Although our focus remains on pursuing a solution through diplomatic means, we are always evaluating other options that will help create space for a negotiated solution,” the National Security Council said in a statement.

However, a US official, who requested anonymity because he was not authorised to talk publicly about internal deliberations, has confirmed to AFP that Obama is “actively” reconsidering sending lethal assistance to Ukraine, but continues to have concerns about the effectiveness of that step and the risks of a ‘shadow’ war between the US and Russia.

US supplies of lethal weapons to Ukraine will escalate conflict — Russian lawmaker http://t.co/YSgpG4ZnQX — ITAR-TASS (@ITARTASSnews_en) February 2, 2015

The official said Obama is specifically concerned about the besieged Ukrainian military’s capacity for using high-powered, American-supplied weaponry. It’s a problem pro-Russian separatists should also be facing if the modern equipment fighting beside them was, in fact, manned by militia.

The US President has also previously argued that no amount of arming the Ukrainians would put them on par with Russia’s full military prowess.

The US so far has limited its supplies to the Ukrainian military to $US118 million nonlethal aid, such as gas masks, body armour, night vision goggles and radar technology to detect incoming shell and rocket fire. About one third of this has so far been delivered.

Speaking in Moscow, Konstantin Kosachev, the head of foreign affairs committee in the Russian parliament’s upper house, warned Washington that supplies of lethal weapons to Ukraine would lead to “further escalation of the conflict,” the Interfax news agency reported.

US secretary of state John Kerry is due to arrive in Kiev on Thursday for discussions.

DEFENCE IN DISARRAY

Will fresh weapons make any difference?

It’s an issue addressed by the analysts who submitted their report at the weekend, reports AFP.

Authors of the report included officials with close ties to the White House, including the former number-three-ranking civilian at the Pentagon, Michele Flournoy, and the former US ambassador to NATO, Ivo Daalder.

Specifically: Ukraine needs light anti-armour missiles to counter “the large numbers of armoured vehicles that the Russians have deployed in Donetsk and Lugansk”, they say.

Others disagree.

“The problem is not the weapons — Ukraine is the fourth-biggest weapons producer in the world,” said Jarabik.

“Their problems lie in things like leadership, management, logistics.”

Western weapons also require specialist training, and that would mean NATO boots on the ground.

“If US forces showed up in Ukraine, even if just for training, it would justify everything the Russian conspiracy theorists have been saying all along,” said Jarabik.

Kiev has been determined not to surrender further ground to separatists, believing Moscow has its eye on several key infrastructure and industrial hubs in order to strengthen the viability of a “breakaway” state in eastern Ukraine.

This includes the railway city of Debaltseve and the key port of Mariupol.

MOSCOW’S WORD GAMES

The conflict in eastern Ukraine which erupted after Russia’s annexation of Crimea in March has so far claimed more than 5100 lives and forced 900,000 to flee since April.

Russia has acknowledged that some of its citizens are fighting among the rebels as volunteers, but rejects the Ukrainian and Western charge that it’s backing the insurgency with troops and weapons.

There are smarter ways to respond to #Russia actions in Crimea than moving US nukes closer to Russia. See http://t.co/bxsJ8zN08A — Steven Pifer (@steven_pifer) February 2, 2015

Western experts say, however, that the sheer amount of heavy weapons under rebel control shows extensive help from Moscow.

This is backed by an ongoing flood of social media images of advanced Russian tanks and advanced missile launchers in clearly identifiable Ukrainian locations — still bearing their Russian insignia.

“While we still have time before the spring, new detachments will be able to receive military training,” the rebel leader said. “We expect mobilisation to yield at least five additional brigades — five motorised brigades, one artillery brigade and a tank brigade.”

Where such equipment and training was coming from was not specified.

Zakharchenko blamed Ukraine for the collapse of peace talks over the weekend and argued that the rebel offensive was the only way to protect residential areas from Ukrainian shelling.

“Force is the only way to protect our cities, villages and streets from the shelling,” Zakharchenko said.

As Moscow ups its rhetoric about US aid, it has itself dramatically strengthened the quality and quantity of military hardware on its borders with Ukraine.

Up to 50 new Su34 combat jets and 20 new Mi-28 ‘Havoc’ attack helicopters are to be stationed on the Crimean peninsula in coming months.

KEY CITY BESIEGED

Since the unrest in eastern Ukraine surged anew in early January, the separatists have made notable strides in clawing territory away from the government in Kiev.

Their main offensive is now directed at Debaltseve — a government-held railway junction once populated by 25,000 people that lies between the rebel-held cities of Luhansk and Donetsk.

Almost 2000 residents have fled in the last few days alone.

Rebel forces have mounted multiple assaults on government positions in Debaltseve but all were repelled, a spokesman for Ukrainian military operations in the east, Andriy Lysenko, said last night.

“The units that have arrived in support of our troops in Debaltseve are counterattacking and denying the enemy the opportunity to complete the encirclement,” he said.

Pro-Russian forces have issued a statement that it has fully encircled the city.

Separatist fighters burst through Ukrainian lines last week in the village of Vuhlehirsk on the road west of Debaltseve, getting access to a ridge overlooking the highway running north from the town.

Yesterday, Associated Press reporters saw Ukrainian tanks shooting from open fields at the tree line on that ridge. Minutes later, the tanks rolled back onto the highway, leaving a heavy trail of mud in their wake, and taking up new field positions a few hundred meters away.

In a coordinated defensive manoeuvre, Ukrainian forces fired barrages from Grad multiple-rocket launchers toward the same area.

Despite government’s insistence it intends to retain control of the city of Debaltseve, rows of trenches near a bridge 15 kilometres to the north suggested a backup plan in case the town falls.

But the battle isn’t all one sided: The rebel stronghold of Donetsk came under heavy, sustained shelling once again in recent days. City authorities said 15 civilians had been killed over the weekend in the fighting, while Ukraine authorities said five soldiers had been killed and 29 wounded overall in the east in the past day alone.

Meanwhile, the leader of the separatists in Donetsk, Alexander Zakharchenko, said new mobilisation plans aim to swell the ranks of rebels to 100,000 fighters.

It’s not clear how many fighters the rebels have now or how many able-bodied men are still available in rebel areas. Zakharchenko didn’t say where he aimed to find apparently tens of thousands of troops.