- Russia looks to have moved thousands of troops from the front lines in Ukraine to defend Kursk.
- One of Ukraine's likely goals with the Kursk incursion was to force Russia to thin out its troops.
Russia appears to be moving thousands of troops from its main eastern front line to support the defense of Kursk after Ukraine's surprise incursion there, according to US sources.
Two unnamed senior US officials told CNN that multiple groups — consisting of at least 1,000 troops each — had apparently been diverted to Kursk.
Analysts believe that weakening Russia's hand along the 600-mile main front line in Ukraine by forcing troop diversions was likely a key objective in Ukraine launching the Kursk attack.
Ukrainian forces first spilled across the border into Kursk in western Russia early last week, in an attack that caught both Russia and the West off guard.
Since then, reports suggest that Ukraine has gained — temporarily at least — about 386 square miles of territory.
Ukrainian soldiers told the BBC that Russian forces had been moved from military flashpoints around the Ukrainian cities of Kharkiv, Pokrovsk, and Toretsk.
On Tuesday, a Ukrainian military spokesperson also told Politico that a "relatively small" number of Russian troops had been shifted from Zaporizhzhia and Kherson, both frontline pressure points.
But two further sources familiar with Western intelligence told CNN that Russia doesn't appear to have redeployed its best-trained units.
Speaking at a White House press briefing on Thursday, national security spokesperson John Kirby was cautious in his assessment of the Russian redeployments.
"We have seen some Russian units being redirected from operations in and around Ukraine to the Kursk area," he said, adding that: "It's not clear right now how many are eventually going to go."
A source familiar with US intelligence told CNN that they haven't seen a "substantial" movement of troops yet.
It remains to be seen if this is the start of a mass redeployment or if Russia will try to minimize those movements out of Ukraine.
Currently, Russia is reported to have moved large numbers of military conscripts from within the country to Kursk's defense.
The removal of a few thousand Russian troops may not have much of an impact in Ukraine, given that Russia is believed to have hundreds of thousands of soldiers on the front lines there.
Meanwhile, the Ukrainian logistical hub of Pokrovsk, in the eastern Donetsk region, is under particular pressure, with the local military administration urging residents to evacuate.
Russia has made confirmed advances nearby, the Institute for the Study of War reported.
Ukraine also had to thin out its own frontline troops to launch the operation in Kursk. Even before the incursion, those troops were vastly outnumbered.
"We don't have enough people to do our job properly," one commander fighting in the Donetsk region told The Wall Street Journal this week.