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.

CNN  — 

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.