Ukraine claims it broke through part of Russia's fearsome defensive line in its counterattack. The next layer is even worse.

• Ukraine claimed it broke through Russian defensive lines in the south of the country.
• However, troops are now coming up against concrete fortifications built by Russia.
• Ukraine's counteroffensive has made only marginal gains thanks to staunch Russian resistance.

Ukraine claims its troops broke through Russian defense lines in the south of the country in a rare success for its counteroffensive.

But, even if the claim is confirmed, by Ukraine's own admission the next stage of the attack will be harder still.