On Tuesday, the Senate confirmed Elbridge Colby as Under Secretary of Defense in a key victory for President Donald Trump, despite attempts by several GOP senators to derail the nomination. Colby, a hawkish defense strategist and co-founder of The Marathon Initiative, was confirmed by a 54-45 vote.
Ranking third in the Pentagon, his role includes briefing Secretary of Defense Pete Hegseth on defense policy. Though a Trump-aligned pick, Colby’s nomination faced criticism from some Republicans who argued that his previous foreign policy positions conflicted with the new administration’s strategic goals. However, a coalition of moderate Republicans and Democrats ultimately secured Colby’s confirmation. Notably, Senator Mitch McConnell (R-KY) voted against the nomination, breaking from his traditionally strong pro-defense stance, despite being one of Washington’s most vocal advocates for U.S. military strength and alliances such as NATO.
“Abandoning Ukraine and Europe and downplaying the Middle East to prioritize the Indo-Pacific is not a clever geopolitical chess move. It is geo-strategic self-harm that emboldens our adversaries and drives wedges between America and our allies for them to exploit,” McConnell puzzlingly claimed in a statement.
Colby’s confirmation marks a significant step in the Trump administration’s broader effort to reshape the Pentagon’s policy leadership in his second term. Widely recognized for co-authoring the 2018 National Defense Strategy under then-Secretary Jim Mattis, Colby played a key role in shifting U.S. military priorities from counterterrorism to great-power competition—particularly with China. His return to a senior defense post represents a full-circle moment. For years, Colby has been one of the most outspoken proponents of reorienting U.S. military strategy toward East Asia.
Colby has consistently warned that the U.S. must be prepared for a potential Chinese move on Taiwan within the next decade. He is the co-founder and principal of The Marathon Initiative, a think tank focused on developing long-term U.S. strategies grounded in geopolitical realism. A prominent advocate of the “limited war” doctrine, Colby argues that the United States should avoid overextending itself in secondary theaters such as the Middle East or Europe, and instead concentrate its efforts on deterrence in the Indo-Pacific region.
He has been openly critical of both neoconservative and liberal internationalist approaches, contending that they overextend U.S. resources. Instead, he advocates for a more focused and cost-effective strategy—one that preserves American dominance in the Pacific while avoiding unnecessary military entanglements. In his 2021 book, The Strategy of Denial: American Defense in an Age of Great Power Conflict, Colby lays out a comprehensive blueprint for countering China. He advocates for structuring U.S. alliances, military posture, and regional commitments around a core objective: preventing Beijing from gaining dominance over Asia.