Ukraine's invasion of Russia is showing how good it is at hitting Putin's weak spots

• Ukraine knows how to exploit Russian President Vladimir Putin's weak spots.
• Its invasion of Kursk undermined Putin's image as a strongman protector of Russian security.
• The attacks have the potential to erode Russians' support for Putin, an expert said.

Russian President Vladimir Putin's authority has long been founded on his image as an uncompromising defender of Russian security.

But Ukraine's audacious invasion of Russia's Kursk province, where its forces are still making advances more than a week into the incursion, badly dents that image.