Colby and his team at the Pentagon: the consequences for US military presence in Europe

On 8 April, the US Senate confirmed the nomination of Elbridge Colby as Under Secretary of Defense for Policy, making him the principal adviser to the Secretary of Defence on shaping national security policy and the third-most senior official in the Department of Defense. During Donald Trump’s first term, Colby served as Deputy Assistant Secretary of Defense for Strategy and Force Development and played a leading role in drafting the 2018 National Defense Strategy. He is known for his view that the United States should focus on deterring and containing China, and reduce its presence in other theatres (Europe and the Middle East). For this reason, his nomination met with opposition from some Republican senators, particularly those especially concerned about Iran’s nuclear programme. This was reflected in a delay of over a month between Colby’s hearing before the Senate committee and the vote on his nomination. Ultimately, only one senator voted against it.

On the very day of President Trump’s inauguration, 20 January, a group of new senior officials were sworn in at the Department of Defense. These appointments did not require Senate confirmation and will play a role in shaping US defence strategy. Particularly noteworthy are Austin Dahmer (Deputy Assistant Secretary of Defense for Strategy) and Alexander Velez-Green (Senior Advisor to the Under Secretary of Defense for Policy). The former previously served as national security adviser to Senator Josh Hawley (also an advocate of prioritising the threat posed by China). The latter also advised Hawley on security issues in the past and most recently worked on defence matters at The Heritage Foundation.

Colby, together with Dahmer and Velez-Green, will have a decisive influence on shaping the new National Defense Strategy and the global posture of the US Armed Forces. A review of this posture (the Global Force Posture Review) is currently underway at the Pentagon, and its outcomes may serve as the basis for potential changes. Both Colby and his associates have for years advocated reducing US troop levels in Europe and even cutting the US Army in favour of strengthening the Navy to confront the People’s Republic of China. All three have authored studies and reports in which they outline detailed proposals they aim to implement within the US Armed Forces.

Commentary

• In shaping defence strategy, Colby will play a particularly important role due to Secretary of Defence Pete Hegseth’s limited experience. So far, Colby has advocated focusing on the most pressing challenges: containing Chinese dominance in the Indo-Pacific and protecting US territory. He has supported reducing US involvement in other parts of the world, although not by withdrawing entirely, but by shifting greater responsibility to allies and partners working with Washington. During his hearing before the Senate Committee on Armed Services, he stated that the United States is not capable of waging simultaneous armed conflicts in multiple theatres, and that Beijing currently poses the primary threat to Washington. He emphasised that the United States’ overriding goal should be to prevent Chinese hegemony in the Indo-Pacific.

• There are indications that the Department of Defense is considering a reduction of the US military presence in Europe. At the end of March, The Washington Post reported on the Interim National Defense Strategic Guidance, allegedly circulated by Secretary Hegseth. According to this report, the guidelines call for concentrating US Armed Forces on threats in the Indo-Pacific region and on homeland security, while accepting greater risk in other theatres (including Europe). During a hearing before the House Armed Services Committee, Department of Defense representative Katherine Thompson declined to confirm whether the Pentagon supports the continued presence of US forces in Europe, citing the ongoing Global Force Posture Review, a comprehensive assessment of US military presence worldwide, which could form the basis for decisions regarding the possible redeployment of US troops abroad. In early April, NBC reported on plans to reduce the US presence on NATO’s eastern flank by as many as 10,000 troops.

• A key factor in determining the extent of US military engagement abroad will be the size of the defence budget the new administration manages to pass. If it turns out to be significantly higher than the one adopted under President Joe Biden – and if it meets the expectations of anti-China hawks regarding deterrence funding in the Indo-Pacific – it may be possible to maintain at least part of the rotational presence in Europe. The continuing resolution in place until the end of the current fiscal year increases spending only slightly (by $6 billion) compared to last year. However, a significant increase in defence expenditure remains possible as part of the ongoing budget reconciliation process. A recent statement by Trump suggests that total spending in this area could exceed one trillion dollars (compared to $886 billion in 2024). The additional funds are expected to be allocated primarily to the modernisation of the Navy and Air Force, an approach aligned with the priorities advocated by Dahmer and Velez-Green (see Appendix).

Appendix. Impact of the prioritisation of the Chinese threat on the Pentagon’s budget according to reports compiled by Dahmer and Velez-Green

In his report ‘Resourcing the Strategy of Denial: Optimizing the Defence Budget in Three Alternative Futures’, published in 2023 by the Marathon Initiative (a think tank co-established by Colby), Austin Dahmer (Deputy Under Secretary of Defense) analyses three possible scenarios for changes to the US defence budget.

1. Maintaining the current level of funding for the Pentagon

Without increasing the Pentagon’s budget by 10% annually, it will not be possible within this decade to maintain US military engagement in Europe, the Middle East, and the Indo-Pacific. Dahmer recommends:

• reduce spending on the US Army by approximately $70 billion annually and shift these funds – alongside other savings – to the Navy and Air Force, to increase their budgets by approximately $40 billion each;

• reduce the presence of US Armed Forces in Europe by approximately 20,000 troops and cut civilian personnel by 5% by completely abandoning the European Deterrence Initiative, which involves rotating troop deployment to NATO’s eastern flank since 2017 (division commands, two Armoured Brigade Combat Teams (ABCTs), one Infantry Brigade Combat Team (IBCT) and one Combat Aviation Brigade (CAB));

• reduce the US Army by the equivalent of three divisions (including two from the National Guard) through the disbandment of four Stryker Brigade Combat Teams (SBCTs) – including two from the National Guard, six Infantry Brigade Combat Teams (IBCTs) – including five from the National Guard, and two National Guard Combat Aviation Brigades (CABs);
• halt numerous land vehicle modernisation and procurement programmes, including those involving M1A2 SEPv3 Abrams tanks, AMPV armoured personnel carriers, AH-64 Apache helicopters, and UH-60 Black Hawk helicopters;
• withdraw all A-10C attack aircraft from the Air Force (currently numbering around 200);

• allocate the budgetary savings thus achieved to the acquisition of additional naval vessels (two frigates and three nuclear-powered attack submarines, beyond the US Navy’s 30-year shipbuilding plan), the accelerated development of B-21 Raider strategic bombers, and an increase in the annual number of F-35 aircraft ordered and produced.

2. Reducing funding for the Pentagon

A reduction in the Pentagon’s budget by approximately 10% would primarily impact the Army, although all branches of the armed forces would be affected by the cuts:

• The Army would lose the equivalent of seven divisions, comprising nine Stryker Brigade Combat Teams (including two from the National Guard), ten Infantry Brigade Combat Teams (IBCTs, including eight from the National Guard), two Armoured Brigade Combat Teams (ABCTs, including one from the National Guard), and five Army Combat Aviation Brigades (CABs, including two from the National Guard). In return, an expansion of air defence structures is proposed, including enhancements to the Patriot missile systems;

• The Navy would prematurely decommission two of the oldest Nimitz-class aircraft carriers and two of the oldest Wasp-class landing helicopter dock (LHD) amphibious assault ships. One of the nine Carrier Air Wings (CVWs) would also be disbanded. The funds thus released would be redirected towards extending the service life of the three oldest Ohio-class submarines (cruise missile carriers armed with Tomahawks), the purchase of three additional Virginia-class attack submarines and two additional guided-missile frigates, as well as accelerating the development of naval unmanned systems;

• The Air Force and the Marine Corps would reduce the number of their air squadrons by an unspecified amount.

3. Increasing funding for the Pentagon

• In the event of a 10% annual increase in the Pentagon’s budget, Dahmer advocates expanding the Army by the equivalent of four divisions (4 ABCTs, 2 SBCTs, 5 IBCTs, and 2 CABs). However, he emphasises that any investments in the US Army should be postponed until the Navy and Air Force have been sufficiently prioritised through investments and additional funding;

• The Navy would extend the service life of 17 ageing Ticonderoga-class cruisers and the three oldest Ohio-class submarines, as well as procure three additional Virginia-class attack submarines and two additional guided-missile frigates. It would also accelerate the development of naval unmanned systems and naval aviation;

• The Air Force would accelerate work on the next-generation B-21 strategic bomber and the Next Generation Air Dominance (NGAD) fighter, while significantly increasing the number of transport aircraft and aerial refuelling tankers being ordered;

• The additional funds would enable the Marine Corps to establish five additional infantry battalions and increase the planned number of F-35B/C fighter squadrons.

In 2024, Alexander Velez-Green (Senior Advisor to the Under Secretary of Defense for Policy) compiled a similar report for The Heritage Foundation – ‘A Conservative Defence Budget for Fiscal Year 2025’. In the report, he highlights the lack of sufficient budget funds to sustain simultaneous US military engagement in Europe, the Middle East, and the Pacific. He argues that:

• The United States must focus on the Indo-Pacific and will need to shift funds, equipment, and personnel from Europe to that region, while maintaining a significantly reduced presence on the European continent;

• European allies must spend more on defence – reaching at least 2% of GDP and aiming for 3% of GDP;

• European allies must take the lead in providing military assistance to Ukraine and assume primary responsibility for Europe’s security, allowing the United States to focus on the Indo-Pacific.