US National Defense Strategy: homeland security and the balance of power in the Indo-Pacific
On 23 January, the US Department of Defense released the National Defense Strategy, a document outlining the Pentagon’s priorities for the coming years. It reaffirms the provisions of the National Security Strategy published in December 2025, focusing primarily on homeland security and the Western Hemisphere. Its secondary priority is ensuring the balance of power in the Indo-Pacific region favours the United States, in order to avoid direct confrontation with China. The document envisages a rapid transfer of responsibility for regional security to America’s partners and allies, with the US maintaining significant but limited military support. This shift applies particularly to Europe, the Middle East and the Korean Peninsula. Within NATO, the US will adjust its contribution to collective defence planning and gradually reduce its military presence in Europe, although the pace of this withdrawal is currently unspecified.
Defence strategy vs. national security strategy
The National Security Strategy (NSS) released December 2025 (see ‘The new US National Security Strategy: a manifesto for a sovereign America in a multipolar world’) signalled a fundamental redefinition of the United States’ role in the world, along with new objectives and assumptions for its foreign and security policy. According to this document, Washington is abandoning its long-standing policy of striving for global dominance and preserving the liberal international order. Instead, it is shifting towards maintaining the balance of power at both the global and regional levels. The NSS emphasises the importance of national sovereignty, adopts a critical stance towards international organisations and outlines a more instrumental approach to America’s partners and allies.
The National Defense Strategy (NDS), issued by the Pentagon, builds on the NSS and aims to operationalise it in practice, although its public version remains relatively general in scope. The NDS reaffirms the rejection of the existing liberal international order, a shift reflected in the actions taken by the Trump administration this January: the intervention in Venezuela, the withdrawal from a range of international organisations, the launch of the Board of Peace as a rival to the United Nations (see ‘Trump’s Board of Peace: an alternative to the UN?‘) and efforts to take control of Greenland (see ‘Trump escalates dispute over Greenland by targeting European allies with tariffs’).
The authors of the NDS have distanced themselves from interventionism understood as a policy of regime change coupled with nation-building, as seen in Iraq and Afghanistan. However, they emphasise that this does not signify a shift towards isolationism. The implicit new model of America’s modus operandi in the military domain is exemplified by recent operations such as ‘Absolute Resolve’ in Venezuela (January 2026) and ‘Midnight Hammer’ in Iran (June 2025).
Challenges, threats and US objectives
In the international security environment outlined in the NDS, top priority is given to challenges and threats to US homeland security and America’s interests in the Western Hemisphere. In accordance with the NSS, this region is viewed as Washington’s sphere of influence, where the presence of strategic rivals must be curtailed. The second priority is China, regarded as a strategic adversary seeking dominance in the strategically critical Indo-Pacific region.
Russia is defined as a persistent yet manageable threat to NATO member states on the eastern flank. It is also described as a nuclear threat due to its possession of the world’s largest nuclear arsenal – which is being continuously modernised and diversified – and its submarine, cyber and space capabilities that could potentially be used against the United States. This perspective is inconsistent with the NSS, which did not even portray Russia as a challenge to the United States, but merely stated that “many Europeans regard Russia as an existential threat”.
Among the challenges and threats outlined in the NDS, Iran ranks fourth, owing to its nuclear programme, whose military objectives are deemed unacceptable by the United States. Next comes North Korea, defined as a threat to South Korea and Japan, two US treaty allies. The final item on the list is the challenge posed by the potential emergence of simultaneous crises and conflicts across multiple theatres – a scenario that could prove problematic due to America’s partners and allies insufficiently investing in their own security.
In light of the security environment outlined in this manner, the NDS establishes the following priorities for the Pentagon: defending US territory; pursuing a policy of deterring China in the Indo-Pacific based on strength rather than confrontation; increasing the responsibility of America’s partners and allies for regional security; and significantly strengthening the US defence industrial base.
Top priority: homeland security and the Western Hemisphere
The NDS assigns top priority to homeland security – not only in terms of defending US territory against attacks by other countries, but also in protecting the borders from illegal immigration and combating drug-related crime. Previous strategies, including the one released in 2018 during Trump’s first term, did not address these challenges at all. They are now described using military terminology, such as an ‘invasion’ of immigrants and ‘narco-terrorism’, in order to justify the use of the US Armed Forces in efforts to counter them. This framing aligns with the previous actions of the current Trump administration, such as deploying US troops to the southern border and conducting military operations against alleged smugglers at sea.
At the strategic level, the NDS also highlights the need to strengthen the defence of US territory against aerial threats. This includes intercepting ballistic missiles through the Golden Dome system. The NDS also calls for investments in countering aerial threats posed by unmanned systems. Its authors further emphasise the indispensability of modernising the US nuclear arsenal, investing in cyber defence and combating Islamist terrorism.
For the first time since the end of the Cold War, the United States is expressing concern over the potential interference of other powers in its immediate neighbourhood, prompting a greater focus on the security of the Western Hemisphere. This entails a revival of the Monroe Doctrine with the so-called ‘Trump Corollary’, which states that the United States must not only maintain its dominance in the Western Hemisphere but also prevent adversaries from deploying their forces or threatening US military capabilities in the region. For the Department of Defense, this will require the ability to secure access to critical areas across the hemisphere, including the Panama Canal and Greenland; the latter is mentioned several times in the document. As an example of this approach, the strategy cites the operation to remove Venezuelan dictator Nicolás Maduro, suggesting that the Pentagon will also be prepared to conduct targeted interventions in other countries across the region.
China: ensuring a favourable balance of power
Given its economic importance, the Indo-Pacific region remains critical to the United States’ future. Consequently, Washington cannot allow another power to dominate this area or restrict US access to it. The strategy identifies China, a power second only to the United States, and its continuously expanding military capabilities as the most significant threat. According to the authors of the document, the United States should therefore strive to establish a balance of power that is favourable to Washington whilst still being acceptable to Beijing. They explicitly emphasise that Washington’s objective is to de-escalate tensions and ensure a peaceful coexistence with China, while adding that the United States must negotiate the terms of this accommodation from a position of strength, in line with the principle of ‘peace through strength’.
In this context, the US Department of Defense mustabove all ensure that US military power is capable of upholding the balance of power in the region. Central to this is the ability to conduct deterrence by denial within the so-called first island chain – a line stretching from Japan through Taiwan and the Philippines to Vietnam. Although the strategy does not mention Taiwan by name, anchoring the deterrence line along the first island chain implies a commitment to defend the island. It is expected that a greater contribution to collective regional security from America’s allies and partners in the Indo-Pacific will form a key element of efforts to establish an effective deterrence, along with maintaining the capability to strike targets across the region.
Shifting responsibility to partners and allies
The NDS sends a clear message that Washington is now prioritising the most consequential and dangerous threats to US interests. This means that America’s partners and allies – particularly those in Europe, the Middle East and on the Korean Peninsula – will be expected to assume responsibility for their own security at a rapid pace, with significant but limited support from the United States. The Pentagon also signals a shift in tone and style when it comes to encouraging them to make greater investments in their own security.
European allies are expected to assume responsibility for collective defence in Europe. The Pentagon has announced that it will monitor compliance with the commitments made at the NATO summit in The Hague, which require member states to raise their defence spending to 5% of GDP, including 3.5% for military expenditure and 1.5% for related needs. The shift in the approach of the US Department of Defense will also entail adjusting targets within NATO’s collective defence planning process and aligning the US military presence in Europe with the new strategy. From Washington’s perspective, European allies should primarily focus on their own security, which implicitly suggests that their involvement in the Indo-Pacific is unwanted.
In the Middle East, Israel is presented as a model ally that, according to the NDS, was unjustly constrained in its military operations by the Biden administration. Alongside US partners in the Persian Gulf, Israel is expected to assume responsibility for deterrence and defence against Iran and its regional proxies. On the Korean Peninsula, South Korea, similarly to America’s European allies, should take the lead in deterring its northern neighbour, with significant but limited support from Washington. With regard to South Korea, the NDS also envisages an adjustment to the US military presence.
