Recent Western intelligence estimates of Russian losses in Vladimir Putin’s invasion of Ukraine raise serious doubts about the Russian military’s ability to sustain its offensive operations for an extended period. With the possibility that Russian forces cannot keep up their wholly unprovoked and unjustified aggression, and may even experience a collapse, the United States, together with its allies, must provide Ukraine with everything it needs to defeat Putin’s military. Time is of the essence.

There is a difference between thwarting Russia’s maximal objectives and Ukrainian victory. Playing for a tie runs the risk that Russia can accomplish in a war of attrition what it failed to achieve in its initial blitzkrieg: the destruction of a functioning, sovereign, independent Ukraine. Moreover, allowing this fight to devolve into an “endless war” risks endangering the lives of many more Ukrainians and jeopardizing continued popular support in the West for assisting Ukraine.

More than 75,000 Russian soldiers have been killed or injured since Putin ordered the full-scale invasion of Ukraine on February 24, according to Rep. Elissa Slotkin, based on a briefing from the U.S. intelligence community. “Over 80 percent of their land forces are bogged down, and they’re tired,” she added. If true, that would be roughly half of all Russian combat forces sent to invade Ukraine.

“I think they’re about to run out of steam,” said British spy chief Richard Moore during the recent Aspen Security Conference, echoing the view of U.S. intelligence that such staggering losses raise questions about Russia’s ability to sustain its campaign. “I think our assessment is that the Russians will increasingly find it difficult to supply manpower [and] material over the next few weeks. They will have to pause in some way and that will give the Ukrainians opportunities to strike back.”

What remains uncertain is whether the Ukrainians, who have executed a brilliant defensive campaign to thwart Russian imperial ambitions, can now transition to the strategic offensive and take back the territory occupied by the invaders.

Morale among the Russian military, low even at the outset of the campaign, is dropping. Reports of soldiers turning on their commanding officers, Russian men seeking to avoid service, and Wagner mercenaries recruiting forces from Russian prisons add to the sense that things are going very badly for Putin. Thanks to the tremendous bravery and determination of Ukrainians, Putin’s goals of decapitating the Ukrainian leadership and occupying much of Ukrainian territory have failed miserably.

Ukrainians, of course, are paying a horrific price for Putin’s decision to invade. Untold thousands have been killed by marauding Russian forces, many the victims of war crimes and acts of genocide, and millions have been displaced. The toll on Ukraine’s economy is staggering.

Ukrainian officials have been reluctant to release figures on the number of their forces killed and injured, but morale is on their side. War is a contest of wills and Russia’s campaign of atrocities and war crimes is hardening the determination of Ukrainians to resist. What is for Putin an imperial war of choice is for them a war of survival. As Putin himself is fond of saying, a cornered rat has no choice but to fight back.

The fight for Ukraine’s east and south is different from the fight for the country’s western half. Different and longer-range weapons systems are required to maintain the Ukrainian military’s momentum and to try and wrestle back occupied territories. Already, the supply of Western weapons systems is making a serious difference. For the first time, Ukrainian artillery can outrange their opponents. U.S. and allied shipments of HIMARS in particular have enabled Ukraine to take out Russian artillery and ammunition depots as well as command posts, leaving already vulnerable Russian forces cut off and exposed. The Biden administration should be accelerating the delivery of even more and longer-range systems to enable the Ukrainians to defeat the Russian forces more quickly and decisively.

Secretary of Defense Lloyd Austin was half right when he said in April that the U.S. wants to “see Russia weakened to the degree that it can’t do the kinds of things that it has done in invading Ukraine.” The White House reportedly was unhappy with Austin’s blunt message, but that is because the National Security Council has consistently been reluctant to provide Ukraine with the decisive assistance it needs. What Secretary Austin failed to say is the only possible way to weaken Russia is to defeat Putin’s invasion of Ukraine.

“While a key goal of the United States is to do the needful to support and defend Ukraine,” Jake Sullivan, President Biden’s national security adviser, said at last month’s Aspen Security Forum, “another key goal is to ensure that we do not end up in a circumstance where we’re heading down the road towards a third world war.”

Providing “needful” support is woefully inadequate. Moreover, concerns about avoiding World War III seem overblown. Although a prudent concern with escalation risks always is wise, the course of this conflict suggests that Putin’s red line is direct U.S. or NATO involvement. Accelerating and increasing military assistance to Ukraine should not come close to breaching it.

Sullivan’s comments also reveal the divide within the administration, with the NSC much more reticent than the State Department and Pentagon to tip the military balance clearly in Ukraine’s favor. While not as bad as some who wrongly and shamefully argued against providing military assistance to Ukraine even before the invasion, the NSC’s position suggests nervousness that Ukraine could actually defeat Russia. And yet that should absolutely be the goal of U.S. assistance: to help Ukraine defeat Russia.

The time when incremental support was sufficient has passed. Ukraine’s needs are known. The United States needs to lead an allied surge to provide a massive U.S. and allied heavy weaponry support package to Kyiv while the Ukrainian military is able to further degrade the Russian forces. The $1 billion defense aid package reportedly being prepared is a welcome step, as would be the decision to give Ukraine American fighter jets, but these tranches of support must come more quickly and more often. The sooner we can help Ukraine defeat the Russian military, the sooner the killing of innocent Ukrainians will come to an end. The sooner that happens, the safer other parts of Europe at risk of Russian aggression will be. And then, perhaps, Putin’s grip on power might be challenged, which would be a welcome relief for many Russians who have suffered under his increasingly fascist rule.

We also need to ratchet up our sanctions on Russia and close any loopholes that enable evasion by Russian banks or oligarchs. The sanctions that already have been imposed have had a major effect on the Russian economy, leading to layoffs and shortages. The Russian ruble, which has strengthened since its dive after the February invasion, has more recently swung wildly in value as Russia’s macroeconomic band-aids start to peel off and long-term economic uncertainty returns. Europe needs to accelerate its plans to reduce its dependence on Russian energy, still an important source of revenue for Putin. Together with serious military assistance for Ukraine, tougher economic sanctions on Putin and his regime will weaken Russia’s ability to carry out its aggression against Ukraine.

Many believe the war cannot be won on the battlefield and that there will be a negotiated settlement. This is probably too optimistic. The sides are too far apart to see what a constructive, enforceable, lasting settlement could look like, and the vast majority of Ukrainians oppose any negotiations that require any concessions from Kyiv.

It is up to Ukrainians to decide when or if to negotiate with Russia, but it is in our interest to strengthen their hand as much as possible right now. We should prepare for the possibility of escalation by the Russian side, not be paralyzed by fear of it. Thanks to the heroism of the Ukrainians, we have an opportunity to deal the Putin regime a serious, maybe even fatal, blow. It will not last long.

Stephen E. Biegun, Eric Edelman, Daniel Fata, and David J. Kramer

Stephen E. Biegun is a visiting instructor at the University of Michigan’s Gerald R. Ford School of Public Policy and served as deputy secretary of state from 2019 to 2021. Eric S. Edelman is counselor at the Center for Strategic and Budgetary Assessments, non-resident senior fellow at the Miller Center of Public Affairs at the University of Virginia, and co-host of The Bulwark’s Shield of the Republic podcast. He served as U.S. ambassador to Finland from 1998 to 2001 and under secretary of defense for policy from 2005 to 2009. Daniel Fata is president of Fata Advisory and was deputy assistant secretary of fefense for Europe and NATO Policy from 2005 to 2008. David J. Kramer is managing director for global policy at the George W. Bush Institute and was assistant secretary of state for democracy, human rights & labor from 2008 to 2009.