Pause in aid has introduced uncertainty into Ukraine’s military planning − forever changing its war calculus

War is a numbers game. Each side involved must marshal the supplies, troops and firepower needed to sustain the fight, thwart advancing armies and, hopefully, prevail.

But it’s also a game of uncertainty.

For the past three years, Ukraine’s military planners have had to approach every battle with a series of cold calculations: How much ammunition is left? How many air defense interceptors can be fired today, without running short tomorrow? Do we have the men and equipment needed to advance or hold position?

But now, with U.S. military assistance on hold and European support constrained by economic realities, that uncertainty is growing.

As an expert on warfare, I know this isn’t just a logistical problem; it’s a strategic one. When commanders can’t predict their future resource base, they are forced to take fewer risks, prioritize defense over offense and hedge against worst-case scenarios.

In war, uncertainty doesn’t just limit options. It shapes the entire battlefield and fate of nations.

On March 3, 2025, President Donald Trump announced a suspension to all U.S. military aid to Ukraine. It followed a fractious Oval Office meeting between the U.S. president and Volodymyr Zelenskyy, after which Trump declared the Ukrainian leader “not ready for peace.”

Two days later, Central Intelligence Agency Director John Ratcliffe announced Washington was also pausing all intelligence sharing and ordered key allies such as the United Kingdom to limit the information they give Kyiv.

National security adviser Michael Waltz has linked the pause to ongoing U.S.-Ukrainian negotiations, stating that weapons supplies and intelligence sharing will resume once Ukraine agrees to a date for peace talks with Russia.

Any pause, no matter how long, will hurt Ukraine.

The U.S. has been the largest provider of military assistance to Kyiv since Russia’s 2022 invasion, followed by the European Union.

While the level of support is debated – it is often skewed by how one calculates equipment donations using presidential drawdown authority, through which the president can dip into the Department of Defense’s inventory – the U.S. has undoubtedly delivered critical weapons systems and a wide range of ammunition.

Though this assistance has decreased U.S. military stockpiles, it has helped Washington invest in its domestic defense industry and expand weapons production.

In addition, while Europe is starting to increase its own defense expenditures, EU members are stuck with flat economic growth and limits on how much they can borrow to invest in their own militaries, much less Ukraine.

This makes the U.S. a critical partner for Ukraine for at least another two years while Europe expands its military capacity.

These conditions affect the design of Ukraine’s military campaigns. Planners in Kyiv have to balance predictions about the enemy’s strengths and possible courses of action with assessments of their own resources.

This war ledger helps evaluate where to attack and where to defend.

Uncertainty skews such calculation. The less certain a military command is about its resource base, the more precarious bold military maneuvers become.

It is through this fog of uncertainty that any pause in assistance shapes the course of the war in Ukraine and the bargaining leverage of all parties at the negotiating table.

The White House has indicated that the pause in military aid and intelligence sharing will be lifted once a date for peace talks is set.

But even if U.S. weapons and intel begin to flow again, Ukrainian generals will have to fight the duration of the war under the knowledge that its greatest backer is willing to turn off the taps when it suits them.

And the consequences of this new uncertain world will be felt on the battlefield.

Ukraine now faces a brutal trade-off: stretch limited resources to maintain an active defense across the front, or consolidate forces, cede ground and absorb the political costs of trading space for time.

Material supply has shaped operational tempo over the course of the war. When Moscow expects Kyiv to be low on ammunition, it presses the attack. In fact, key Russian gains in eastern Ukraine in 2024 coincided with periods of critical supply shortages.

Russia used its advantage in artillery shells, which at times saw Moscow firing 20 artillery shells to every Ukrainian artillery shell fired, and air superiority to make advances north and west of the strategic city of Avdiivka.

Looking to the front lines in 2025, Russia could use any pause in supplies to support its ongoing offensive operations that stretch from Kherson in southern Ukraine to Kharkiv in the north and efforts to dislodge Ukrainian units in the Russian Kursk region.

This means Ukraine will have to decide where to hold the line and where to conduct a series of delaying actions designed to wear down Russian forces.

Trading space for time is an old military tactic, but it produces tremendous political costs when the terrain is your sovereign territory.

As such, the military logic of delaying actions creates political risks in Ukraine – sapping civilian morale and undermining support for the government’s war management.

This dilemma will drive where and how Ukraine weights its efforts on the battlefield.

First, long-range strike operations against Russia will become increasingly less attractive. Every drone that hits an oil refinery in Russia is one less warhead stopping a Russian breakthrough in the Donbas or counterattack in Kursk. Ukraine will have to reduce the complexity of its defensive campaign and fall back along lines deeper within its own territory.

Second, Russia doesn’t fight just on the battlefield – it uses a coercive air campaign to gain leverage at the negotiating table. With U.S. military aid on hold, Moscow has a prime opportunity to escalate its strikes on Ukrainian cities and infrastructure, forcing Kyiv into painful choices about whether to defend its front lines or its political center of gravity.

From Vietnam to Ukraine, airpower has historically been a key bargaining tool in negotiations.

President Richard Nixon bombed North Vietnam to force concessions. Russia may now do the same to Ukraine.

Seen in this light, Russia could intensify its missile and drone campaign against Ukrainian cities and infrastructure – both to weaken defenses and to apply psychological and economic pressure. And because Kyiv relies on Western assistance, including intelligence and systems such as U.S.-built Patriot surface-to-air missiles to defend its skies, this coercive campaign could become effective.

As a result, Ukraine could be faced with a horrible choice. It may have to concentrate dwindling air defenses around either key military assets required to defend the front or its political center of gravity in Kyiv. Interception rates of Russian drones and missiles could drop, leading to either opportunities for a Russian breakout along the front or increased civilian deaths that put domestic pressure on Ukrainian negotiators.

The real problem for Ukraine going forward is that even if the U.S. resumes support and intelligence sharing, the damage is done.

Uncertainty, once introduced, is hard to remove. It increases the likelihood that Ukraine’s leaders will stockpile munitions to reduce the risk of future pauses, rather than use them to take the fight to Russia.

And with battlefield decision-making now limited, Ukraine’s military strategists will increasingly look toward the least worst option to hold the line until a lasting peace is negotiated.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Benjamin Jensen, American University School of International Service

Benjamin Jensen does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.