Retired U.S. Army General Mark Hertling said Saturday that Russia is currently on “defense” while Ukraine is able to “pick where they attack” as the war between the two continues to rage on.

“Early RU [Russia] goals were beyond their capability. Reducing the goals didn’t help. Now, RU’s defending in more places against a growing conventional UA [Ukraine] threat and an expanded guerilla war. UKR has transitioned to the offense and can pick where they attack; RU is now on the defense,” he wrote on Twitter in a thread.

The retired general added that Russian troops on the ground have proven to be “poorly-led, ill-trained and with low morale” and that they were unable to execute combined arms operations (CAOs) in Ukraine. CAOs is a combination of infantry, tanks, offensive and defensive fire powers, aviation, and intel.

Meanwhile, the British Ministry of Defense said this week that Russia’s failure to “enforce low-level battle discipline” had led to recent “poor performance of Russia’s forces,” adding that failures by Russian tank crews caused “heavy attrition” in combat.

“Russia came into this fight thinking they could execute a ‘Desert Storm-like offensive’ that would be completed in a few days. This was delusional,” Hertling tweeted Saturday. “They lacked the leadership, training, and equipment to do it. Given RU culture and systems, they aren’t capable of fixing this.”

Ukraine currently doesn’t have the training or type of organizations or equipment to carry out large scale CAOs, according to Hertling, even though troops are “relatively” well-trained and have high morale as they continue to receive support from their government and citizens.

However, Hertling clarified: “Don’t get me wrong, UA can execute defensive operations, counterattacks, hasty attacks and smaller scale CAOs. They are not yet capable of large-scale CAOs over large areas. But, they are adapting, training with allies, incorporating new equipment, and doing so very quickly.”

The retired general added that Ukraine knows something that Russia doesn’t, which is that “you can’t win wars with artillery or air alone. Those may affect the outcome, or even prep the battlefield for future fights, but a force can’t regain ground with ‘fires’ alone. You must do it with maneuver forces in CAOs.”

Last month, Hertling said that the High Mobility Artillery Rocket Systems (HMARS) that were provided to Ukraine are a “game changer,” adding that Russian forces are now “in dire shape.”

The HIMARS were provided as part of a security aid package of $270 million that the White House said would be sent to the Eastern European country, and have been a massive help to Ukrainian forces.

Newsweek reached out to the Russian Foreign Ministry for comment.