Ukrainian servicemen of 79th brigade cover a 105 mm howitzer with a camouflaged net near the frontline outside of Marinka as the war between Russia and Ukraine continues in Donetsk Oblast, Ukraine on February 28, 2024.

Editor’s Note: Mark T. Esper served as the US defense secretary during the Trump administration and is the author of the book “A Sacred Oath: Memoirs Of A Secretary Of Defense During Extraordinary Times.” He serves on the board of The McCain Institute. Esper serves on the board or as a strategic advisor for a handful of aerospace and defense-related companies. The views expressed in this commentary are his own. View more opinion on CNN.

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As Russia resurges in Ukraine and proxy fights expand across the Middle East, one critical question weighs heavily in everyone’s minds: Is the United States still a credible ally willing to lead the free world? Whether Congress chooses to provide the continued financial support Ukraine, Israel and Taiwan desperately need will go a long way toward answering this question. And make no mistake, it is not just our allies who are wondering. Our adversaries are paying close attention as well.

Secretary of Defense Mark Esper testifies during a House Armed Services Committee hearing on July 9 in Washington, DC.

For the past few months, Congress has been locked in a stalemate over approving this funding. Meanwhile, our partners’ need for this assistance continues to grow, particularly in Ukraine where soldiers are rationing ammunition due to dangerously low stockpiles and civilian neighborhoods are requiring more air defense systems to protect against indiscriminate Russian barrages. Without renewed US support, the arms pipeline to Ukraine will continue to dwindle over the coming months, directly impacting what happens on the battlefield. The recent loss of the eastern Ukrainian city of Avdiivka in the face of a nonstop Russian onslaught has been blamed in part on an inadequate supply of Western artillery rounds. With the scale and scope of this scarcity increasing with each passing month, we could see city after city fall into Russian President Vladimir Putin’s hands as Washington’s dysfunction continues.

This additional aid is not a matter of charity. In the case of Ukraine, over 60% of the military assistance Congress allotted since the beginning of the war is benefiting the US economy. Funds approved to arm Ukraine are helping replenish American weapons stockpiles and build new systems, which in turn has delivered a major cash infusion to plants and workers in more than 30 states. It also has had a salutary impact on the revitalization of the US defense industrial base, which is especially important as we prepare for the greater threat that Communist China presents.

Republicans are right to raise concerns about the nation’s debt and deficits. Both are exorbitant and unsustainable. But these important fiscal matters should not trump national security, nor should they force officials to choose one regional problem over another or even over border security. At the end of the day, it furthers America’s own security interests and values to help our democratic partners defend themselves against the world’s autocracies. We are far better off in a world where Ukraine successfully repels the Russian invasion, Israel dismantles the Iranian-backed Hamas terrorists and Taiwan deters a Chinese attack than we would be living with the alternatives.

If we fail to provide continued support, the negative ramifications will be significant. For one, it would cause our allies around the world to doubt America’s leadership and resolve. We are already seeing considerable concern from international partners as we waver on Ukraine. It is true that our NATO partners need to do much more, beginning with meeting their decade-old commitment to spend 2% of their GDP on defense, and our southern border needs to be secured too, but neither of these are sufficient reasons to starve Kyiv of much-needed US weapons and other materiel.

It is also true that this war could last for many more years, requiring US and other Western support for just as long. While President Joe Biden did a respectable job rallying NATO to Ukraine’s defense two years ago, history will judge his skittish reluctance to provide Kyiv the weapons it needed when it needed them, time and time again, as a major reason why Ukraine’s counteroffensive failed and why this war will drag on. These are still not worthy reasons, though, to deny the brave people of Ukraine the arms they need to push the Russians back, exhausting Moscow in the process and possibly leading to a resolution that favors Kyiv.

A local resident cleans debris in front of the railway station destroyed by a Russian missile attack in Kostyantynivka, Donetsk region, on February 25, 2024, amid the Russian invasion of Ukraine.

It is not just our European allies who are watching with apprehension. As China continues to threaten the Indo-Pacific, key partners such as Taiwan, Japan, South Korea and the Philippines are closely monitoring whether Washington will fail Kyiv. If the United States is unwilling to help Ukraine beat back a Russian invasion that does not require the commitment of US forces, how can Taiwan trust we will come to their aid if China moves against them — an act of aggression that could require a much greater investment of American treasure and potentially involve our troops as well?

Failing to approve additional funding only emboldens our adversaries. It is no longer credible to suggest we can treat China, Russia and Iran as disconnected threats. This authoritarian axis has been working in a coordinated manner with the goal of undermining American leadership and dismantling international rules and norms. Each is watching closely to see how the US responds to their attacks and provocations. How effectively (or not) we counter one will absolutely inform the calculus of the others.

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Just as America’s disastrous withdrawal from Afghanistan emboldened Russia to invade its neighbor, walking away now from Ukraine will further incentivize aggression from this authoritarian axis. If Putin is successful in Ukraine, there is little evidence to suggest he will be content to stop there, which increases the chances the United States and NATO could eventually get drawn into a direct confrontation with Russia. Some of our allies are physically fortifying their borders for such a future.

A short distance away in the Middle East, Iran and its proxies are likely to further destabilize the region. Absent bolder action from Washington, this will put our close ally Israel and US forces under even more pressure. And if Chinese leader Xi Jinping believes American resolve will easily crumble as we increasingly look inward, the odds of Chinese military action against Taiwan will only increase as he may calculate that even a stalemate would eventually turn in China’s favor.

Both our allies and adversaries are connecting the dots, even if certain American officials are unable or unwilling to do so. We cannot leave any doubt about our credibility as an ally or the strength of our resolve, and we must not abandon our partners on the front lines of this fight. Politics must be set aside, and politicians who spurn allies, coddle autocrats and argue for American retrenchment should be ignored. While engaging abroad, deterring conflict and helping friends defeat aggression is the right thing to do, it is also admittedly expensive; however, the consequences of not doing so are far, far greater in the long run. Leadership is a heavy cross to bear, indeed, but the benefits of doing so — especially in the face of clear threats — will always outweigh the costs and favor the United States.