US Secretary of State Antony Blinken and British Foreign Secretary David Lammy are to make a joint visit to Ukraine in a show of solidarity to Kyiv against Vladimir Putin’s invasion.
They announced the trip at a press conference at the Foreign Office in London.
Mr Lammy said: “On Russia and Ukraine, today I can confirm that Tony and I will be traveling to Kyiv this week - the first joint visit of this kind for well over a decade.
“We are the closest of allies, so I'm delighted that we will travel together, demonstrating our commitment to Ukraine.”
Mr Blinked added: “I think it's a critical moment for Ukraine in the midst of what is an intense fall fighting season, with Russia continuing to escalate its aggression.
“Aggression against civilians, against critical infrastructure, and, of course, against Ukrainian forces. We see it ramping up its attacks on cities, people, in particular, targeting the energy infrastructure, electricity, all in advance of the coldest months.
“Putin's winter playbook of weaponising energy and electricity.”
America’s top diplomat was holding talks with Sir Keir Starmer and Mr Lammy over the Ukraine and Middle East wars.
The discussions in London were being billed as on a strategic level, rather than responding to particular incidents.
Putin’s military has been using “glide bombs” launched far behind frontlines to attack towns and cities in Ukraine with devastating impact.
His war, launched in February 2022, has left hundreds of thousands of Russian soldiers dead or wounded, with similarly high casualties among Ukraine’s forces, as well as thousands, if not tens of thousands of civilians being killed.
Iran is also believed by European intelligence chiefs to have recently supplied Russia with a significant batch of short-range ballistic missiles.
Mr Blinken confirmed Washington is to deepen sanctions on Iran after Tehran provided ballistic missiles to Russia.
"The United States will be announcing further sanctions on Iran later today, including additional measures on Iran Air. "We expect allies and partners will be announcing their own new measures on Iran as well," Mr Blinken said.
The US has warned Iran that providing ballistic missiles to Russia to use in Ukraine would "constitute a dramatic escalation", he said.
"Russia has now received shipments of these ballistic missiles and will likely use them within weeks in Ukraine against Ukrainians," he added.
The Iranian ballistic missile system, which has a maximum range of 75 miles, will allow Russia to target its arsenal further from the front line, he said.
Ahead of the meetings with Mr Blinken, Mr Lammy said: “The special relationship has been cherished on both sides of the Atlantic for more than 80 years, but together we are committed to supercharging our alliance to bring security and growth to Brits and Americans alike.
“In a more volatile and insecure world, it is even more important that we are highly aligned nations.”
Sir Keir is due to fly to Washington for talks with Joe Biden on Friday.
The State Department said Mr Blinken was also due to discuss when in London the Indo-Pacific region and the AUKUS defence pact between the US, Australia and Britain.
Meanwhile, Ukraine struck Moscow and western Russia on Tuesday in one of its biggest ever drone attacks, forcing the closure of major airports and a main road into the capital, according to officials.
Ukraine launched swarms of attack drones, with at least 20 destroyed over the Moscow region and 124 more over eight other regions, say Russian sources.
One woman was killed in the capital and dozens of homes were destroyed, they added.
As Putin’s forces advances in eastern Ukraine, Kyiv has been trying to take the war to Russia with a surprise attack on its western Kursk region on August 6 and increasingly large drone attacks deep into its territory.
Overnight Russian drone and missile attacks injured at least three people, damaged buildings and caused fires across Ukraine, authorities said today.
The air force reportedly shot down 38 out of 46 Russia-launched drones during an overnight attack across 13 regions.
