Ukraine says it has taken out another bridge that is vital for Russian forces occupying the southern Kherson region.
It says the bridge on the dam at Nova Kakhovka is now impassable.
It comes just weeks after the key Antonivsky Bridge was put out of action by Ukrainian forces.
Ukraine is waging a counter-offensive towards Kherson city, which Russia captured in the early days of the war.
“The destruction of the road bridge of the Nova Kakhovka dam was ensured, with the result that it was taken out of operation,” the Ukrainian army’s Operational Command South posted to Facebook.
In a daily intelligence update, UK defence officials said Ukrainian precision strikes were likely to have made the road crossing over the Dnieper River “unusable for heavy military vehicles”. Nova Kakhovka lies about 55km north-east of Kherson.
Russian forces had only succeeded in making superficial repairs to the main Antonivsky Bridge, the officials said, which Western military sources said was “completely unusable” after a Himars artillery rocket attack last month.
The main rail bridge near Kherson was also further damaged last week, the UK update said.
“Even if Russia manages to make significant repairs to the bridges, they will remain a key vulnerability,” the UK defence ministry said.
It added that thousands of Russian troops west of the river were now “almost certainly reliant on just two pontoon ferry crossing points” for ground resupplies.
Military analysts say there is a growing risk of the troops being cut off from the rest of main Russian occupying forces.
The attack is part of a Ukrainian effort to isolate Russian troops, with the ultimate goal of recapturing the entire region.
If it proves successful the ambitious campaign would provide a boost for Kyiv by retaking from Russia the only regional capital it has so far captured since the invasion in February.
Kherson, which had a population of about 290,000 before the war, is currently administered by Moscow-backed officials.
Last month, Russia said its military focus was no longer only on eastern Ukraine but on its southern regions of Kherson and Zaporizhzhia too.
According to Russia’s Tass news agency, officials in Kherson city have started moving forward with plans to hold a referendum on formally joining Russia.
The US has accused Russia of preparing to annex parts of occupied Ukraine illegally.
But Iryna Vereshchuk, Ukrainian minister for reintegration of the temporarily occupied territories, said this week that any referendum held in occupied-regions would never be internationally recognised.
She also advised Ukrainians remaining in Russian-held areas to evacuate, adding that 5,300 people had left the Kherson region in the last five days.