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The United States’ defence policy under Donald Trump’s second term administration promises to be more assertive and focused on national interests, which will have a significant impact on global security, including Ukraine and Israel. According to an analysis by the Royal United Services Institute (RUSI) published on 16 May 2025, the key changes in US strategy will be to prepare for a potential conflict with China, redistribute responsibilities among allies, strengthen the defence of its own territory, and reduce defence spending. These changes create both opportunities and challenges for Ukraine and Israel.
New US defence strategy: key areas
According to RUSI, the Trump administration seeks to implement the “America First” principle, which involves ending current wars, preventing new conflicts, restoring US military power, and strengthening the defence industry. At the same time, allies, including Ukraine and Israel, will face greater demands to fund their own security and regional stability. The new National Defence Strategy, which is being developed by Under Secretary of Defence for Policy Albright Colby, is expected to be completed by the end of August 2025. This document will be concise and focused on priorities such as countering China as the “principal threat”, defending US territory, and modernising the armed forces.
Despite his limited experience in the defence sector, Defence Minister Pete Hegseth has been actively promoting the idea of “peace through strength”. However, his position has come under pressure due to the Signal app scandal and the dismissal of several advisers. Nevertheless, Hegseth and his team plan to cut the Pentagon’s budget by 8% (approximately $50 billion) over five years, reallocating funds to priority programmes such as nuclear modernisation, Virginia-class submarines, unmanned systems and missile defence.
The use of military force: lessons and prospects
Trump, despite his peacemaker rhetoric, is ready to use military force more often, avoiding lengthy ground operations. In March 2025, the United States launched strikes against the Houthis in Yemen, which ceased after a temporary truce was announced. However, the Houthis continue to threaten Israel, which could lead to an escalation. RUSI notes that Trump prefers targeted strikes using naval and air forces, as was the case during his first term, when the US eliminated ISIS leader Abu Bakr al-Baghdadi and Iranian General Qassem Soleimani.
For Ukraine, this means that the United States is unlikely to provide “strategic guarantees” in the event of a ceasefire or peace agreement with Russia. American support for NATO, in particular Article 5 on collective defence, also appears weaker than ever. For Israel, the situation is more complicated: The United States is actively persuading Israel to refrain from striking Iran’s nuclear facilities, but in the event of a large-scale Israeli attack and an Iranian counterattack, the United States could be drawn into a protracted conflict.
Impact on Ukraine
For Ukraine, a key challenge will be the US demand that European allies, including NATO members, increase defence spending to 5% of GDP. This goal, which many consider unrealistic, could lead to tensions at the NATO summit in The Hague on 24-26 June 2025. The United States plans to withdraw up to a third of its combat forces from Europe, particularly from Germany, Poland and the Baltic states, which will weaken the Alliance’s military presence in the region. This will force European countries, including Ukraine, to take more responsibility for their own security.
The US withdrawal of “strategic support” Ukraine in the event of a peace agreement with Russia could complicate negotiations. At the same time, the reduction of the US presence in Europe opens up opportunities for Ukraine to strengthen its role in regional security if it can build up its own defence capabilities and receive support from European partners.
Challenges for Israel
Israel finds itself in a delicate situation due to the US policy of containment towards Iran. The United States is building up its military presence in the Middle East, but at the same time is exerting diplomatic pressure to prevent Israeli strikes on Iranian nuclear facilities. In the event of an escalation of the conflict with Iran, Israel can count on American support, but only if the conflict does not escalate into a prolonged war, which Trump is trying to avoid.
At the same time, Israel, like other allies, will face US demands to increase spending on its own defence and the purchase of US weapons. This may increase the financial burden on the Israeli budget, but at the same time strengthen military cooperation with Washington.
The new US defence policy under the Trump administration is creating a challenging landscape for Ukraine and Israel. Ukraine will have to adapt to the diminishing American presence in Europe, seeking new formats of cooperation with NATO and European partners. Israel will have to balance its own security interests with American efforts to contain Iran. Both countries will have to invest more in their own defence to meet the new realities of the US “transactional” policy.
By the end of the summer of 2025, when the new US National Defence Strategy is published, the picture will become clearer. Ukraine and Israel should prepare for new challenges by strengthening their own positions and seeking alternative sources of support in the context of the transformation of American policy.
Source: Royal United Services Institute(RUSI) analysis, 16 May 2025.
Author: Aleksandr Potetiuiev
