By Tom Balmforth
KYIV (Reuters) -Ukraine told critics of the pace of its three-month-old counteroffensive to "shut up" on Thursday, the sharpest signal yet of Kyiv's frustration at leaks from Western officials who say its forces are advancing too slowly.
Since launching a much vaunted counteroffensive using many billions of dollars of Western military equipment, Ukraine has recaptured more than a dozen villages but has yet to penetrate Russia's main defences.
Stories in the New York Times, Washington Post and other news organisations last week quoted U.S. and other Western officials as suggesting the offensive was falling short of expectations. Some faulted Ukraine's strategy, including accusing it of concentrating its forces in the wrong places.
Moscow says the Ukrainian campaign has already failed. Ukrainian commanders say they are moving slowly on purpose, degrading Russia's defences and logistics to reduce losses when they finally attack at full strength.
"Criticising the slow pace of (the) counteroffensive equals ... spitting into the face of (the) Ukrainian soldier who sacrifices his life every day, moving forward and liberating one kilometre of Ukrainian soil after another," Ukraine's Foreign Minister Dmytro Kuleba told reporters on Thursday.
"I would recommend all critics to shut up, come to Ukraine and try to liberate one square centimetre by themselves," he said at a meeting of EU foreign ministers in Spain.
NATO Secretary-General Jens Stoltenberg told CNN that Ukrainian commanders deserved the benefit of the doubt.
"Ukrainians have exceeded expectations again and again," he said. "We need to trust them. We advise, we help, we support. But... it is the Ukrainians that have to make those decisions."
After months of fighting their way through heavy minefields, Ukraine's forces have finally reached the main Russian defensive lines in recent days, south of the village of Robotyne which they captured last week in Western Zaporizhzhia region.
They are now advancing between the nearby villages of Novopokropivka and Verbove, looking for a way around the anti-tank ditches and rows of concrete pyramids known as dragon's teeth that form Russia's main fortifications visible from space.
A breakthrough would provide the first test of Russia's deeper defences, which Ukraine hopes will be more vulnerable and less heavily mined than areas its troops have traversed so far.
A Ukrainian commander in the area told Reuters last week that his men had breached the most difficult line, reaching less heavily defended areas, and now expected to advance more quickly. Reuters could not independently verify this.
Kyiv rarely gives details of its offensive operations.
In a statement on Thursday, Deputy Defence Minister Hanna Maliar reported unspecified successes near Novopokropivka, without giving details.
She also said Ukrainian forces were advancing near Bakhmut, in the east, the only city Russia captured in its own offensive earlier this year. Heavy battles were engulfing villages south of the city, she said.
Oleksandr Syrskyi, commander of Ukraine's ground forces, reported a "positive dynamic" near Bakhmut.
DRONE ATTACKS WITHIN RUSSIA
Ukraine has also stepped up drone attacks on targets deep within Russia and in Russian-controlled territory in Ukraine.
Russia's Defence Ministry said it had destroyed a new Ukrainian drone over the Bryansk region in southern Russia.
It had earlier reported overnight drone attacks in Bryansk and said it had shot down a missile fired on Crimea, occupied and annexed by Russia in 2014.
The previous night, Moscow reported attempted Ukrainian drone strikes in six Russian regions, including one that caused a huge fire at a military air base in Pskov in northern Russia, damaging several giant military transport planes on the tarmac.
While Ukraine rarely comments directly on specific attacks inside Russia, President Volodymyr Zelenskiy appeared to boast of the Pskov attack twice on Thursday.
"The results of our weaponry -- new Ukrainian weaponry -- 700 km away," he said in his nightly video address. "And the task is to do more."
Ukraine's Western allies generally forbid Kyiv from using weapons they supply to attack Russian territory, but say Ukraine has a right to attacks military targets with its own weapons.
The assaults in recent weeks, including several on central Moscow over the past month, have brought the war home to many Russians for the first time after 18 months during which Russia has subjected Ukraine to countrywide air strikes.
Russia is also facing the aftermath of a mutiny two months ago by Wagner, a private army that had formed the main attack force of its own winter offensive earlier this year. Wagner's leader Yevgeny Prigozhin and his main lieutenants were killed in an air crash last week.
The Kremlin has denied that it was behind the crash. President Vladimir Putin had called Prigozhin's mutiny treason but had promised not to punish him for it.
On Thursday, Prigozhin's right-hand man, Dmitry Utkin, a neo-Nazi former military intelligence officer whose call-sign Wagner gave the mercenary force its name, was buried at a cemetery near Moscow under guard of Russian military police. Prigozhin was buried near St Petersburg on Tuesday.
(Writing by Peter Graff; Editing by Alex Richardson and Cynthia Osterman)