incursion

Defence sources have told the BBC that suspicion had fallen on a "state actor" being responsible for the incursions.

The government has warned that those behind recent drone incursions over US airbases will be "shown the full force of the law".

“To date, installation leaders have determined that none of the incursions impacted base residents, facilities or assets,” the statement added.

Ukraine launched a surprise incursion into the Russian region on 6 August and still holds territory there.

Ukraine's surprise incursion into Russia's Kursk region is faltering as Russian troops have pushed Kyiv's offensive backwards.