A major political dispute is intensifying in the UK over whether government spending should prioritise defence or welfare.

Former defence secretary Lord Robertson warned that Britain’s security is “in peril,” arguing that the country cannot rely on what he called an “ever-expanding welfare budget.” He also highlighted concerns over a widening gap between defence and social spending.

Robertson urged a shift in funding priorities, accusing Chancellor Rachel Reeves of limiting military investment while welfare costs rise. His comments have triggered strong debate within Labour and across Parliament.

Former minister Lord Hutton backed the warning, calling it a defining moment for Sir Keir Starmer’s leadership, while urging urgent action on defence funding.

Harriet Harman also suggested revisiting policies like the pension “triple lock” to redirect public funds toward security spending.

The debate comes as reports suggest the Treasury has asked the Ministry of Defence to consider billions in possible cuts, adding pressure to an already strained budget outlook.

Britain is facing an estimated £28 billion defence funding gap over the next four years, according to parliamentary estimates.

The government has pledged to raise defence spending to 2.5% of GDP, with a longer-term target of 3%, but military officials say this still leaves a shortfall.

Chancellor Rachel Reeves has ruled out borrowing to cover the gap, insisting fiscal rules must be maintained and major spending decisions will be reviewed later.

The issue has exposed sharp political divisions, with critics arguing that welfare expansion is being prioritised over national security.

Defence spending debates have also revived scrutiny of Britain’s wider budget structure, including pressure on welfare systems such as Universal Credit.

Opposition figures argue cuts are being considered to fund military expansion, while the government insists reforms are focused on efficiency and fraud reduction.

Treasury minister James Murray rejected claims of a “zero-sum” choice between welfare and defence, saying both areas are being strengthened.

Left-wing critics, including MP Diane Abbott, warned that cutting welfare for defence spending risks political backlash and public resentment.

The dispute is unfolding as Britain increases support for Ukraine and reassesses long-term defence commitments through NATO.

Defence Secretary John Healey continues to push for higher military funding amid growing global instability.

The government insists there is no internal paralysis, but delays in publishing a long-term defence investment plan have fuelled criticism of internal disagreement.

The debate now reflects a wider question facing the UK: how to balance social welfare with rising security demands in an increasingly unstable world.