The deal between Moscow and Kyiv to unblock Ukrainian grain exports may offer a way forward to a possible ceasefire in the five-month conflict, said former German chancellor Gerhard Schroeder, a friend of Russian president Vladimir Putin.
The first grain-carrying ship to leave Ukrainian ports in wartime safely anchored off Turkey's coast on Tuesday and is due to be inspected on Wednesday.
"The good news is that the Kremlin wants a negotiated solution," Mr Schroeder told Stern weekly and broadcasters RTL/ntv on Wednesday, adding he had met Putin in Moscow last week.
"A first success is the grain deal, perhaps that can be slowly expanded to a ceasefire," he said.
Mr Schroeder, chancellor from 1998 to 2005, has criticised the war in Ukraine but refused to condemn Putin.
Meanwhile, Russia has accused the United States of being directly involved in the conflict in Ukraine and not just supplying Kyiv with arms.
Russia's defence ministry, headed by an ally of Putin, said comments made by Vadym Skibitsky, Ukraine's deputy head of military intelligence, to Britain's Telegraph newspaper showed that Washington was entangled in the conflict.
Skibitsky told the paper there was consultation between US and Ukrainian intelligence officials before strikes and Washington had an effective veto on intended targets, but that US officials were not providing direct targeting information.
"All this undeniably proves that Washington, contrary to White House and Pentagon claims, is directly involved in the conflict in Ukraine," the Russian defence ministry said in a statement on Tuesday.
"It is the Biden administration that is directly responsible for all Kyiv-approved rocket attacks on residential areas and civilian infrastructure in populated areas of Donbas and other regions, which have resulted in mass deaths of civilians."
There was no immediate reaction from the White House or Pentagon to the ministry's assertions.
The Pentagon did deny, however, Moscow's claims that Russia had destroyed six US-made HIMARS missile systems since the start of the Ukraine war. Russia regularly claims it has hit HIMARS but has yet to show proof.
Donbas: 'Just Hell'
Ukraine's General Staff on Wednesday catalogued continued heavy Russian shelling of Kharkiv and other towns and villages in its vicinity, as well as air and missile strikes on civilian objects. Moscow denies deliberately targeting civilians.
Ukrainian president Volodymyr Zelenskiy on Tuesday said that despite arms supplies from the West, his country's forces could not yet overcome Russian advantages in heavy guns and manpower.
"This is very much felt in combat, especially in the Donbas. ... It is just hell there. Words cannot describe it."
Reuters was not able to verify battlefield reports.
Germany's Schroeder said the future of Donbas was complicated. The traditional industrial heartland in Ukraine's east has seen some of the war's heaviest fighting.
"A solution based on the Swiss cantonal model will have to be found," he said, adding it would have to be seen if Putin would go back to a pre-war "contact line" in a ceasefire.
Switzerland has 26 semi-autonomous cantons or provinces.
Solutions to crucial problems such as Crimea, which Russia annexed in 2014, could be found over time, "maybe not over 99 years, like Hong Kong, but in the next generation", he said.
Britain's defence ministry said the rail link connecting Russian-occupied Kherson in southern Ukraine with Crimea was highly unlikely to be operational due to a Ukrainian strike against a Russian ammunition train.
Russian forces are likely to repair the railway line in a few days, although it will remain a vulnerability for Russian forces and their logistical resupply route from Crimea into Kherson, Britain said in an intelligence update on Twitter.
Russia sent tens of thousands of troops into Ukraine on February 24th in what it calls a "special military operation". Kyiv and the West have condemned it as an unprovoked war of aggression.
At a UN conference on Tuesday, Igor Vishnevetsky, deputy director of the department for non-proliferation and arms control of the Russian foreign ministry, refuted all allegations of "unprovoked aggression". He also added that Moscow was convinced a nuclear war "must never be fought".
Meanwhile, a July 22nd UN-brokered deal to unblock Ukrainian grain exports had an initial success as the first loaded ship since Russia's invasion safely anchored off the Turkish coast.
The vessel, the Sierra Leone-flagged Razoni was at the entrance of the Bosphorus Strait, which connects the Black Sea to world markets, around 1800 GMT on Tuesday, some 36 hours after leaving the Ukrainian port of Odesa.
The ship, which is carrying 26,527 tonnes of corn to Lebanon, is due to be inspected on Wednesday in Turkey.
The exports from one of the world's top grain producers are intended to help ease a global food crisis.
Known as Europe's breadbasket, Ukraine hopes to export 20 million tonnes of grain held in silos and 40 million tonnes from the harvest now under way, initially from Odesa and nearby Pivdennyi and Chornomorsk.
Russia has called the Razoni's departure "very positive" news. It has denied responsibility for the food crisis, saying Western sanctions have slowed its exports.