One year ago, with Ukraine's borders surrounded by what seemed to be a superior military force, many U.S. officials and analysts predicted a swift Russian blitz to Kyiv.
But after president Vladimir Putin sent his more than 150,000 arrayed troops across the border, it soon became clear that a dual reassessment was in order: The Russian invaders were less potent than advertised, and the Ukrainians were unexpectedly stubborn and wily in the defense.
Some of the Russian troops weren't even aware they were on a combat mission until Ukrainian bullets came cracking past them, according to U.S. officials. Meanwhile, Ukrainian forces stalled a massive Russian supply convoy through direct attacks and by destroying a key bridge. Only one week into the invasion, Putin's men were plagued with food and fuel shortages, morale running similarly low.
"Putin assumed that Ukraine was an easy target, Putin assumed that Kyiv would easily fall, and Putin assumed that the world would stand by," Defense Secretary Lloyd Austin said during a speech in Brussels last week. "But the Kremlin was wrong on every count."
Ukrainian forces were armed with more than grit.
They also had years of U.S. and NATO military training, plus American-made weapons, like anti-armor Javelins and anti-aircraft Stinger missiles. These made Russian vehicles vulnerable to ambush, and left Russian helicopter and jet pilots wary of flying over Ukrainian positions. Indeed, many airmen did not return from their sorties.
Despite astonishing losses of soldiers and vehicles, Putin has shown no inclination to end the conflict anytime soon. And despite its tenacity, Ukraine has also taken significant casualties and is not able to produce enough of its own weapons and ammunition to keep up the fight.
Ukraine, after thwarting the advance on its capital, and later routing Russian forces from Kharkiv, now largely faces a battle of supply.
"When this war began, Russia had a larger population, a much bigger defense budget, a bigger military, bigger industrial base. So, this became an industrial war and a war of industrial bases," said Seth Jones, director of the International Security Program at the Center for Strategic and International Studies. "This is why Western industrial support has been so critical."
A key question now is, despite massive military aid packages and a promise to send even more, could the U.S. strategy ultimately result, not in a Ukrainian victory, but a stalemate in a years-long war of attrition?
Impact of US military support
The U.S. has committed nearly $30 billion dollars in security assistance to Ukraine since the invasion began, and Austin has led the 54-nation "Ukraine Defense Contact Group" to help coordinate support from others.
That U.S. aid includes 160 American howitzers with a million artillery rounds, more than 100 million rounds of small-arms ammunition, 8,000 tank-killing Javelins, 109 Bradley fighting vehicles, secure communications equipment, body armor and much more.
While expressing thanks, Ukrainian President Volodymyr Zelenskyy has consistently asked the West for more advanced weapons like long-range missiles and fighter jets.
The Biden administration has so far rejected some of these requests and been slow to entertain others.
It has nevertheless incrementally expanded the types of weapons it has helped procure for Ukraine as the war has progressed -- from handheld launchers, to sophisticated air-defense platforms, to armored vehicles, to precision multiple-launch rocket systems.
There is some sense behind this incrementalism, according to Mick Mulroy, an ABC News contributor who served as a CIA officer and deputy assistant secretary of defense.
"We needed to balance to make sure that we didn't draw this into a larger NATO-versus-Russia, World War III, scenario. We needed to balance that and we needed to see how effective the Ukrainians were going to be with the support we provided them," Mulroy said.
By now the Ukrainians have proven they can quickly learn to make great use of advanced weapons, and the U.S. could be doing more to help them achieve victory, according to Mulroy.
Jones said if the U.S. wants Ukraine to succeed, and not just settle into stalemate, more is needed.
US too risk averse?
"The administration has done a good job, but I think it's been sometimes too slow and too risk averse," Jones said.
In June, the Pentagon announced the U.S. would send High Mobility Artillery Rocket Systems (HIMARS) with precision ammunition capable of hitting targets up to 50 miles away.
"Ukrainian forces are now using long-range rocket systems to great effect, including HIMARS provided by the United States, and other systems from our allies and partners," Austin said in July.
But so far, the administration has declined to send longer-range Army Tactical Missile System (ATACMS) ammunition for the HIMARS. With a range of 190 miles, ATACMS would allow Ukraine to reach out nearly four times further than with the currently provided rockets.
"It's our assessment that they don't currently require ATACMS to service targets that are directly relevant to the current fight," Undersecretary of Defense for Policy Colin Kahl told reporters in August.
"In a ground war, longer range actually ends up being really helpful. So I think we're at a point right now for the Ukrainians to try to take back additional territory ... continuing to give them assistance is helpful. But what they also need now, and what the U.S. has not been willing to give, is long-range fires, like the ATACMS," he said.
That extra reach would be especially important in retaking Crimea, according to Mulroy.
"If they have any chance of taking Crimea, they're going to have to reach pretty far in there," he said.
The administration has changed course on some types of aid it originally wrote off as impractical, most notably Abrams tanks. For other items, such as large MQ-1C drones and F-16 fighters, which some experts say could make a difference in the fight, there's no indication that's being reevaluated.
While there are arguments to be made that money for fighter jets could be used to greater effect elsewhere, and that pulling Ukrainian pilots away from the war for a lengthy period of training might not be a worthwhile tradeoff, it's harder to apply such concerns to sending longer-range missiles for the HIMARS Ukrainians are already trained on and have been using in combat for months.
Fear of escalation
A less-publicized reason for hesitance over sending ATACMS and other sophisticated weapons is fear of escalation between Russia and the West. It's a fear the Kremlin has deliberately tried to inculcate.
In September, Russian Foreign Ministry spokeswoman Maria Zakharova warned the U.S. would be crossing a "red line" were it to supply Ukraine with longer-range weapons.
While threatening language from Putin and his subordinates is concerning, it would not make sense for Russia to extend its aggression into NATO territory, according to Jones, who said, "They're having enough problems right now in Ukraine."
"With an industrial base that's stretched, with an army that can't even defeat a second or third-rate power, the idea that they would expand this to include NATO countries ... would be very irrational," Jones added.
But Putin's decision to invade in the first place was perhaps less than rational, and even if too conventionally depleted to match the U.S. and its allies, Russia still wields an awesome unconventional arsenal.
"The cloak has been pulled back -- Russia is not a superpower, militarily, at all. But they have 6,000 nuclear weapons," Mulroy said.
While Putin has not followed through on several previous threats, the prospect of Ukraine using long-range American missiles to hit targets across its border would likely be the greatest "red line" test of the conflict so far.
Jones and Mulroy both believe Ukraine could put ATACMS to better use pushing Russian forces out of its territory than by striking the Russian mainland.
Either way, while a beleaguered Kyiv could be morally and strategically justified in deciding to hit the land of its aggressor, land which is being used to launch attacks on Ukraine and to supply the Russian war effort, such a move could have unintended consequences.
"I'm suggesting that we give them what they need to fight and repel them out of Ukraine, but not taking strikes in Russia, which could then basically shore up president Putin's support," Mulroy said.
The U.S. could also offer ATACMS on condition they only be used within Ukraine. Once the missiles were in Ukraine, the restrictions could always be loosened if the U.S. deemed necessary.
But ultimately, the goals of not upsetting Russia and of helping Ukraine defeat Russia's invasion are incompatible -- the most effective U.S. support for Ukraine will tend also to be the most at risk of angering Putin.
"I think the U.S. has to make a decision here about whether it helps Ukraine retake the territory that has been illegally taken through conquest and then annexed, or you're going worry about not escalating with the Russians" Jones said.
What 'victory' means remains vague
The Biden administration has been vague when it comes to defining what victory means for Ukraine, and in stating the ultimate goal of U.S. aid.
America's top general offered the following during a press conference in November:
"We will continue to support Ukraine for as long as it takes to keep them free, sovereign, independent, with their territory intact," chairman of the Joint Chiefs of Staff Gen. Mark Milley, said.
However, 10 minutes later during the same press conference, Milley said a military victory is not on the horizon:
"The probability of a Ukrainian military victory, defined as kicking the Russians out of all of Ukraine ... the probability of that happening any time soon is not high, militarily," he said. "It may be a political solution where, politically, the Russians withdraw. That's possible. You want to negotiate from a position of strength."
So far, neither Moscow nor Kyiv have shown any interest in voluntarily resolving the conflict or willingly ceding ground, preferring instead to adjudicate matters on the battlefield.
Mulroy hopes the West will "start equipping and supporting the Ukrainians to win, and not just 'not lose' -- and that means aircraft, long-range fires, and developing a sustainable logistical pipeline that ensures no break in the support getting to the front lines."
Jones also emphasized the importance of increasing aid for Ukraine, if victory is the goal.
As for escalation, Jones inverted the usual thinking, putting onus on the invaders.
"This is on the Russians in the end, and I would focus on supporting the Ukrainians and worry a little bit less about the Russians, who got themselves into this mess."
Biden and members of his Cabinet have said the U.S. will continue to support Ukraine "as long as it takes."
But victory as Zelenskyy defines it -- complete reclamation of all occupied territory, with Russian reimbursement for damages as well as long-term security guarantees -- could take more than just prolonged support. More powerful support might be needed.