Ukrainian soldiers were forced to communicate only by radio and phone when intense Russian jamming disrupted their satellite internet connection, according to a report by the Washington Post.
The Ukrainian brigade in northern Kharkiv lost connection to drone and communications systems as Russian forces began their incursion on 10 May, the newspaper reported.
It is reportedly the first time that Russian electronic warfare has completely knocked out the Ukrainian Starlink connection since the start of the war.
A Ukrainian soldier told the Washington Post the disruptions prevented Ukrainian forces from conducting basic reconnaissance.
The Institute for the Study of War (ISW) said it was "notable" Russian forces were able to achieve such a widespread effect and said they may have waited to deploy a new electronic warfare adaptation during the beginning of the operation.