Last week, Ukrainian national forces lost the strategic railway hub at Debaltseve despite committing thousands of troops and hundreds of armored vehicles to its defense.
Less than a month earlier, they lost the Donetsk airport, where troops won praise for putting up a long, tough fight before they were defeated in a city that has been a rebel stronghold.
Ukraine's losses were so bad that President Petro Poroshenko sought a cease-fire, as he did last summer, when his military lost two-thirds of its armored vehicles to Russian tanks, artillery and rockets.
"The Ukrainians knew they can't counter Russian tanks, Russian armored vehicles and Russian unmanned aerial vehicles," said retired general Wesley Clark, a former NATO commander.
"They knew they were at a military disadvantage, and sought protection" under the cease-fire agreement signed Feb. 11 in Minsk, the capital of Belarus.
Poroshenko cites this imbalance when asking the West for defensive weapons, such as anti-tank missiles, advanced drones and long-range anti-artillery targeting equipment.
Germany and France fear that giving Ukraine those weapons would escalate the conflict.
President Obama postponed any decision, saying he wants to see if the cease-fire holds.
The cease-fire has been observed in most areas.
On Monday, a Ukrainian military spokesman said separatist troops continued to mass near the eastern port city of Mariupol, attacking with artillery fire.
Ukraine will not pull back its heavy weapons as required by the cease-fire agreement until the attacks end, Lt. Col. Anatoliy Stelmakh told reporters.
For any cease-fire to hold, Ukraine's military needs more equipment to enforce it, Clark said.
He pointed out that 29,000 separatist fighters are supplied with advanced Russian weaponry and are joined on the battlefield by as many as 14,000 Russian troops, including infantry, special operations, armor and artillery units.
Russia denies sending troops or weapons to eastern Ukraine.
Ukraine has committed all but a handful of military units to hold the cease-fire line but lacks weapons comparable to what the separatists have, said Philip Karber, president of the Potomac Foundation, which has helped former Soviet bloc countries join NATO.
Both Clark and Karber traveled to Ukraine this month and consulted with military leaders there.
The two analysts collaborated in April on a report that Clark presented at the White House describing Russia's strategy in eastern Ukraine.
Karber has long advocated providing Ukraine with defensive weapons, and Clark now supports that position, too.
"Moscow's story line is that the separatists' ranks consist of coal miners and farmers beating the best of the Ukrainian military," Clark said.
"It isn't so."
The rebel force includes many Russians because it couldn't get enough separatists to join the fight, he said.
Many separatist leaders are Russian citizens.
The separatists are armed with modern Russian tanks with night vision equipment, rocket launchers and advanced Russian drones.
The weapons imbalance has influenced how the war is being fought and has contributed to the repeated encirclement and routing of Ukrainian forces, Karber said.
The Ukrainians don't have anti-tank weapons for infantry that can penetrate Russian tanks, so they can't fight a mobile battle, Karber said.
So far, Ukraine has relied most on its artillery, a blunt weapon that has wreaked havoc on civilian areas in separatist-held territory and is thought to account for 80% of separatist casualties, Karber said.
But they're running low on ammunition, and the bulk of the Ukrainian military is now at risk of being overrun or having their lines broken, he said.
Ukrainian units' "stocks are getting low enough it's beginning to offset their ability to protect their infantry," he said.
Ukraine's military problems go beyond inadequate weapons, said Derek Chollet, who left the Defense Department in January as assistant secretary for national security affairs.
He said Ukraine's military started out weak because the previous regime had slashed defense spending.
It also suffered from leadership failures, having four defense ministers in the past year, Chollet said.
Ukraine's new leaders asked the Pentagon to help root out corruption, improve management and provide battlefield advice and training.
Chollet said that even if Ukraine received more weapons from the West, Russia would continue to dominate the battlefield.
"The kinds of weapons and the amounts under consideration aren't going to fundamentally change the military balance," Chollet said.
Source: USA Today