In response to Russia's invasion, the United States and numerous other countries have provided Ukraine with both lethal and non-lethal military aid, as well as intelligence assistance. In doing so, they are attempting to strike a balance between supporting Ukraine and avoiding further escalation of the conflict.

Although the United States has provided foreign and military aid to Ukraine since the collapse of the Soviet Union, those amounts increased after Russia's invasion of Crimea in 2014.Footnote ¹ From the invasion of Crimea through early October 2021, the United States “allocated more than $2.5 billion in security assistance to Ukraine.”Footnote ² During the Obama administration, the United States restricted itself to “provid[ing] Ukraine [with] nonlethal security assistance, such as body armor, helmets, vehicles, night and thermal vision devices, . . . advanced radios, . . . medical kits, and other related items.”Footnote ³ The Trump administration announced in 2017 that it would also provide lethal military aid.Footnote ⁴ Notably, military aid to Ukraine became a centerpiece of the first impeachment of former President Donald Trump, who placed a hold on $391 million in security assistance to Ukraine in an attempt to pressure Ukrainian President Volodymyr Zelensky to announce investigations into then former Vice President Joseph Biden and his son's ties to Burisma, a Ukrainian energy company.Footnote ⁵ Using a variety of programs, the Biden administration has continued to provide “nonlethal aid and defensive lethal weaponry to Ukraine.”Footnote ⁶ This aid accelerated in the runup to the February 2022 invasion. In December 2021, the administration used “Presidential Drawdown Authority (PDA), by which the President can authorize the immediate transfer of articles and services from U.S. stocks without congressional approval in response to an ‘unforeseen emergency,’” to provide $200 million in defense materials to Ukraine.Footnote ⁷

Security assistance has accelerated dramatically since Russia's invasion on February 24. From the invasion through late April, the United States provided “more than $3.7 billion” in security assistance to Ukraine, bringing the total of such assistance since 2014 to “more than $6.4 billion.”Footnote ⁸ Among other items, the United States has provided thousands of Javelin missiles, “a shoulder-held anti-tank weapon that shoots heat-seeking rockets . . . towards targets up to” 2.5 miles away, as well as Stinger anti-aircraft weapons, “hundreds of ‘Switchblade’ drones, which are designed to be sent crashing into enemy targets before exploding,” and so-called “ghost drones,” which reportedly are similar to Switchblade drones but “were ‘rapidly developed by the [U.S.] Air Force in response specifically to Ukrainian requirements.’”Footnote ⁹

Provision of security assistance to Ukraine has drawn bipartisan support in Congress. Congress has repeatedly authorized additional funding,Footnote ¹⁰ including $3.5 billion in military assistance in March.Footnote ¹¹ In April, Congress passed the Ukraine Democracy Defense Lend-Lease Act of 2022 by a voice vote in the Senate and a vote of 417 to 10 in the House, and Biden signed it into law on May 9.Footnote ¹² The Act, which invokes the World War II-era Lend-Lease Act of 1941, “allow[s] the United States to deliver arms to Ukraine more speedily by doing away with a variety of procedural hurdles” and “essentially allow[s] the Biden administration to gift vast tranches of arms to Kyiv.”Footnote ¹³ By the end April, the Biden administration had “nearly exhausted the emergency military funding Congress approved in March” and asked Congress to approve “$33 billion in additional defense, economic and humanitarian assistance for Ukraine,” of which “[r]oughly half . . . is expected to fund new military assistance.”Footnote ¹⁴ In mid-May, Congress passed an additional aid package, exceeding Biden's request and providing $40 billion in assistance.Footnote ¹⁵ While $20 billion of the total is devoted to military aid, the bill also includes, among other funding, “more than $8 billion in general economic support for Ukraine, nearly $5 billion in global food aid to address potential food shortages sparked by the collapse of the Ukrainian agricultural economy, and more than $1 billion in combined support for refugees.”Footnote ¹⁶

Although the United States is the largest provider of military assistance to Ukraine,Footnote ¹⁷ many other countries are also giving military assistance to Kyiv. By late March, roughly two-thirds of NATO member states had committed to providing lethal military aid,Footnote ¹⁸ and the European Union (EU) had committed €1 billion in military support for Ukraine, including funding for both military equipment and non-lethal aid, such as medical supplies.Footnote ¹⁹

Some of the assistance commitments represent a significant shift in foreign policy. Germany, for example, departed from its historical ban on weapons exports into conflict zones and committed to sending anti-tank weapons and anti-aircraft systems from its stockpiles.Footnote ²⁰ Finland and Sweden, which have long pursued neutrality, have both provided weapons to Ukraine.Footnote ²¹

Some countries have only committed to providing non-lethal aid. Ireland has stated that its financial contributions as part of the EU aid package will only go to non-lethal aid, such as body armor and medical supplies.Footnote ²² Japan has committed to sending military supplies, such as bullet proof vests, but has not promised to send weapons.Footnote ²³

The United States has also provided Ukraine with intelligence. After concerns from Congress about reports that the United States was not providing Ukraine with “real-time targeting data that would enable Ukraine's military to strike” Russian positions, the White House reportedly “modified existing guidance for the Pentagon and U.S. spy agencies on sending intelligence data to the Ukrainian government to clear the way of any bureaucratic roadblocks to information sharing.”Footnote ²⁴ In a subsequent congressional hearing on March 17, National Security Agency Director Gen. Paul Nakasone noted that he had never seen better sharing of actionable intelligence in his career than the sharing with Ukraine, and Defense Intelligence Agency Director Army Lt. Gen. Scott Berrier called the intelligence sharing with Ukraine “revolutionary in terms of what we have been able to do.”Footnote ²⁵ Media reports citing U.S. officials have indicated that U.S. intelligence sharing has helped Ukraine, among other efforts, to move air defenses out of the way of incoming Russian strikes.Footnote ²⁶

The assistance provided to Ukraine has provoked debates over how much and what precise types of aid countries can give to belligerent parties consistent with international law. Media reports noted internal U.S. government debates about whether providing certain types of weapons and intelligence to the Ukrainian government would make the United States a cobelligerent in the conflict.Footnote ²⁷ Outside experts, including former U.S. government lawyers, have argued that the UN Charter's regulation of the use of force displaced earlier laws regarding neutrality between parties to an armed conflict, and therefore that providing weapons and other support to Ukraine—the victim of an unlawful aggression—neither violates international law nor makes the sending countries parties to the conflict.Footnote ²⁸

Setting aside the legal debate, however, U.S. “officials acknowledge that the judgments of government lawyers are valuable only up to a point, and that all that really matters is the judgment of one person: Mr. Putin.”Footnote ²⁹ As an anonymous U.S. official warned, “The American legal definitions of what constitutes entering the war are not Mr. Putin's definitions.”Footnote ³⁰

Nonetheless, as Ukraine pushed back Russian forces in parts of the country and fighting shifted to eastern Ukraine, the United States and other countries have delivered more and more significant military and intelligence assistance to Ukraine. Early in the conflict, U.S. officials reportedly attempted to calibrate military assistance so as not to provoke escalation, including by focusing on providing Ukraine with shorter range weapons that Putin was less likely to regard as a threat to Moscow.Footnote ³¹ By mid-April, however, the United States provided Ukraine with “heavier weaponry . . . including artillery, armored personnel carriers and helicopters, to help Ukrainian forces hold off a major Russian offensive” in eastern Ukraine, and the United Kingdom pledged to “provide antiship missiles and armored vehicles, among other systems.”Footnote ³² The United States also reportedly increased intelligence sharing with Ukraine, shifting from merely providing intelligence to Ukraine “about Russian capabilities in Donbas and Crimea” to “providing targeting data that would enable the Ukrainians to take offensive action to recapture those territories, which Moscow's forces occupied in 2014.”Footnote ³³ When asked at the end of April about U.S. goals, U.S. Defense Secretary Lloyd Austin said after a visit to Kyiv, “We want to see Russia weakened to the degree that it can't do the kinds of things that it has done in invading Ukraine.”Footnote ³⁴

The United States and its allies have continued to refuse certain types of assistance, however, including providing fighter jets to Ukraine.Footnote ³⁵ The United States and NATO also repeatedly declined Zelensky's request that they establish a no-fly zone over Ukraine, citing concerns about escalation because a no-fly zone would require shooting down Russian aircraft.Footnote ³⁶ In a press conference on March 4, NATO Secretary General Jens Stoltenberg said that “we . . . believe that if we [established a no fly zone], we'll end up with something that could end in a full-fledged war in Europe, involving many more countries, and causing much more human suffering.”Footnote ³⁷ On March 15, White House Press Secretary Jen Psaki stated that “[the President] continues to believe that a no-fly zone would be escalatory, [and] could prompt a war with Russia.”Footnote ³⁸ Putin himself has also said that a no-fly zone would be “participating in the armed conflict.”Footnote ³⁹

Escalation remains a serious concern. Beginning days after the invasion, Putin and other officials have suggested that Russia might use nuclear weapons.Footnote ⁴⁰ In late April, Russian Foreign Minister Sergey V. Lavrov warned that the West “must not underestimate” the possibility of nuclear conflict and accused NATO of “in essence . . . engag[ing] in a war with Russia through a proxy.”Footnote ⁴¹ Russia has also launched strikes on weapons deliveries from Western nations.Footnote ⁴²

As battles with Russian forces continue, the United States and its allies are engaging in longer term planning to continue military assistance to Ukraine. After meetings in Germany with “more than 40 nations helping Ukraine with military and humanitarian aid,” Defense Secretary Austin announced on April 26 the formation of a U.S.-led “Ukraine Contact Group,” through which “defense ministers and military chiefs” of allied countries will meet monthly to coordinate assistance.Footnote ⁴³ Ukraine continues to rely on many Soviet-made weapons, which has led Western allies to source non-standard ammunition—so called because it is “incompatible with those used by the United States and many allied nations, which are generally known as NATO-standard ammunition”—from Eastern Europe.Footnote ⁴⁴ The United States and other allies have also facilitated transfers of Soviet-made equipment and weapons systems to Ukraine from countries that still have them in their arsenals because the Ukrainian military is already familiar with them, avoiding the need for additional training.Footnote ⁴⁵ Countries have reportedly agreed to such transfers on the basis of U.S. and other countries’ promises to “backfill” the transfers, replacing the older weapons systems being transferred with newer and more advanced Western models.Footnote ⁴⁶ The United States and allies have begun to train Ukrainian military officials to operate Western military systems,Footnote ⁴⁷ part of a longer term strategy to “transition [Ukraine] to NATO-standard weapons . . . so that it can further take advantage of the West's vast stockpiles of ammunition.”Footnote ⁴⁸

Russia's invasion also appears poised to shift the strategic map of military alliances in Europe. After visiting Kyiv in late April, U.S. Secretary of State Antony Blinken asserted that “when it comes to Russia's war aims, Russia is failing, Ukraine is succeeding,” and Russia's military “is dramatically underperforming.”Footnote ⁴⁹ Blinken also noted that Russia “sought to divide the West and NATO,” but the result has been “exactly the opposite . . . and, indeed, new countries [are] considering applying for membership.”Footnote ⁵⁰ On May 18, Finland and Sweden applied to join NATO.Footnote ⁵¹ In a statement, Biden said that he “warmly welcome[s] and strongly support[s]” the countries’ applications and that he “look[s] forward to working with the U.S. Congress and our NATO Allies to quickly bring Finland and Sweden into the” alliance.Footnote ⁵²