Kyiv (Ukraine) (AFP) -
Ukraine on Thursday claimed a military breakthrough in its counter-offensive against Russian invaders as US Secretary of State Antony Blinken, on a surprise visit to Kyiv, unveiled another $2.8 billion in military aid.
Ukraine said its forces made gains both in the north, the south and the east, prying back land seized by Russia which had hoped for a swift victory when it attacked nearly seven months ago.
In the area around Kharkiv, Ukraine's second city, forces penetrated 50 kilometres (30 miles) beyond Russian lines and 'liberated' more than 20 towns and villages, senior military official Oleksiy Gromov said.
Hoping to build the momentum, Blinken secretly travelled to Kyiv for his second trip during the war, passing through dark hallways with sandbags in the sealed presidential compound to discuss the military aid with President Volodymyr Zelensky.
Presenting a state award to Blinken, the Ukrainian leader voiced gratitude for the 'enormous support' from the United States, saying it was 'a guarantee that we can return our territories.'
Blinken vowed that the United States would keep up assistance 'until the aggression ceases and Ukraine is fully sovereign'.
'You have our word -- and our track record,' said Blinken, sporting a tieless suit across from the unshaven Zelensky in his now signature military green T-shirt.
'What we see is costs on Russia that are already extraordinary and they are going to get heavier and heavier,' Blinken said.
The latest package includes $675 million to be shipped shortly in arms, ammunition and supplies and another $1 billion in longer-term loans and grants for Ukraine to buy more US equipment.
The State Department also approved $1.2 billion for 18 other nations seen as facing threats from Russia including Baltic states, Moldova and Georgia, which both have breakaway regions backed by Moscow.
A day after the United Nations said there were 'credible reports' of Russia forcing Ukrainian children into its territory, Blinken started his trip by visiting toddlers injured in the war at a hospital.
In a room with toy trucks and alien figurines, he arrived with a basket of stuffed animals, announcing, 'I brought some friends.'
'The spirit of your children sends a very strong message around the world,' he said.
Blinken also knelt down to pat Patron, a fabled Jack Russell terrier that has helped Ukraine's military find more than 200 mines laid by Russian forces.
- Allies pledge support -
In a coordinated display of resolve, Biden was to speak by telephone with leaders of allies on Ukraine and Defence Secretary Lloyd Austin met his counterparts at Ramstein air base in Germany.
'Now, we're seeing the demonstrable success of our common efforts on the battlefield,' Austin said.
Amid Ukraine's reports of gains, Russia also trumpeted battlefield successes, saying it had hit five command posts and downed 13 drones on Thursday.
Addressing a forum in Moscow, Prime Minister Mikhail Mishustin said Russia had withstood Western sanctions over the war better than expected, estimating that GDP had fallen just over one percent year-on-year in the first six months of 2022.
Russia's central bank expects a contraction of four to six percent for the year, while Blinken cited an estimate of an even steeper drop.
'Unprecedented sanctions were imposed on our country. But their initiators did not achieve their main objective. They failed to undermine our financial stability,' Mishustin said.
But as the war grinds on, both sides have increasingly been facing a crunch on military supplies with US officials saying Russia, long a major defence exporter, was buying drones from Iran and large quantities of rocket and artillery shells from North Korea.
Speaking at Ramstein, top US General Mark Milley said there was 'significant consumption of munitions' by Ukraine that will need to be addressed by allies.
In new pledges to Ukraine, Norway offered 160 Hellfire missiles and night-vision equipment, Germany offered winter supplies and The Netherlands joined Germany with demining training.
- US aid tops $15 bn -
The latest package by the United States -- Ukraine's largest supplier -- includes 105mm howitzers, precision-guided GMLRS rockets and artillery ammunition.
It brings US military aid to Ukraine since the invasion to $15.2 billion.
Among the most efficient weapons sent by Washington are the HIMAR multiple rocket launch systems, which are paired with GMLRS rockets that can reach targets up to 80 kilometres (50 miles) away.
But Kyiv is seeking ATACMS -- precision-guided, medium range tactical missiles capable of striking 300 kilometres.
The United States has so far refused as it fears the missiles could land in Russian territory, sparking an even bigger conflict.
'Right now, the policy of the United States government is that we're not sending ATACMS,' Milley said.
'The range of the HIMARS is sufficient to meet the needs of the Ukrainians as they are currently fighting.'