Toretsk (Ukraine) (AFP) - First there was a teasing crackle of small arms fire then a burst of sharp bangs as Ukrainian assault infantry fired their US-made grenade launder at the Russian positions opposite.
The frontline in this part of the Donetsk region in eastern Ukraine has been fairly stable since 2014, when Moscow's proxy forces in the so-called Donetsk People's Republic (DNR) seized an enclave.
But many Western weapons -- like the Mk-19 automatic grenade launcher -- have only arrived on this battlefield since February this year, when Russia escalated the conflict with a full-scale invasion.
On Wednesday, soldiers of Ukraine's 5th Regiment of Assault Infantry loaded their launcher from a crate of 40 millimetre grenades and set it on its low tripod in a thicket of trees and brush near their position.
Russian troops were dug in less than 800 metres (half-a-mile) away.A jet -- it wasn't clear whose -- roared overhead and then rifle shots rang out and bullets whizzed audibly but harmlessly overhead.
The Russians had taken what the Ukrainians jokingly called "the bait".
An order came in over the radio and the Mk-19 operator shouted "Glory to Ukraine" then opened up, firing a sustained burst of high-explosive grenades toward the source of the incoming gunfire.
The belt of ammo used up, the soldiers scrambled to dismantle the 35-kilogram (77-pound) weapon and to move back to cover, in case the Russian forces decided to respond with an artillery strike.
On a frontline that has remained more-or-less stable for more than eight years, familiar tactics had been shaken up for a few moments by the introduction of a US-made weapon, giving Ukraine a slight edge.
If that seems almost too neat an example of what has happened over recent weeks, when Ukrainian forces have successfully counterattacked Russian forces on several fronts, it also demonstrates the limits of the strategy.
For the men of the 5th Regiment, on one hill overlooking the Russian-held town of Gorlivka, the Mk-19 is a morale booster.
But it is not a game changer.
"We definitely need more artillery," said an officer with the 5th, who gave his name as "Sergiy".
"When it comes to artillery, they still have an advantage so we can't return fire equally.
"We are firing more precisely now, but with fewer strikes.Meanwhile, they are not very precise, but they fire more."
No breakthrough
The Ukrainian forces fighting along this Donetsk front -- in a line south from the town of Bakhmut through the region's coal-mining villages and conical slag heaps -- have not made any breakthrough.
Russian forces have in recent weeks captured a group of villages south of Bakhmut, and the town and its remaining residents have been under shellfire for months.
The reason, the troops explain, is that the Russian forces here are still supplied from the former separatist enclave -- now claimed as "annexed" territory by Moscow -- on established routes.
Unlike the Russian troops holding the territories captured this year, who in places crumbled in front of last month's counter-offensive, Moscow's local forces have had experience holding the enclave since 2014.
And Russia's massive superiority in artillery still counts here.
Successful Ukrainian offensives in Kharkiv to the north and Kherson to the south used advanced Western weapons like HIMARS rocket artillery in support of daring armoured manoeuvres to encircle towns.
Mismatched fatigues
But, the Ukrainian soldiers say, if they are to win a final victory and expel the Russians from the east, they will need more Western supplied weapons and ammunition -- a lot more -- and quickly.
"We have to hold them here, and Europe should understand this.Better to hold them here, and not in Europe," said Sergeant Mykola Lupiy, urging European and US taxpayers to see the value in defeating Russia.
The soldiers of the 5th Assault Infantry wear a mismatch of Western kit.
Some are in US-style fatigues, one has French body armour and another a British set in desert camouflage that he said he chose because it fitted him better.
Most carry one version or another of the Soviet-designed Kalashnikov series of assault rifles, but one has a futuristic-looking Belgian-made FN F2000, which fires NATO's standard 5.56mm ammunition.
The regiment's badge incorporates the familiar outline of the US defence department's Pentagon as a background to the 5th's red lightning bolt -- because "we need so many US arms" an officer joked.
