BAE Systems chief executive Dr Charles Woodburn has warned that Britain has been complacent about the danger of foreign attack and must adapt more rapidly to a security environment transformed by Russia's war in Ukraine, cyber operations and increasingly autonomous weapons.

He described the current threat level as the highest he has encountered in his lifetime.

Woodburn welcomed the government's commitment to raise core defence expenditure to 3.5 percent of gross domestic product by 2035, but said substantially more funding would be required to reach it.

Current plans are expected to lift spending to only 2.68 percent of GDP by 2030, leaving a steep and expensive increase for the following five years.

Independent fiscal analysis has likewise identified the unfunded route to the 2035 target as a central challenge.

In a rare interview, Woodburn said the character of warfare had changed "quite profoundly." Russia and Ukraine, he noted, have become "incredibly adept" at deploying drones, counter-drone systems and autonomous technologies, forcing Britain to understand those capabilities and develop credible means of countering them.

He also cautioned that lethal systems capable of operating without direct human control were approaching practical use.

Britain maintains a policy of meaningful human involvement in decisions involving force, but Woodburn said potential adversaries might not observe the same restraint.

The Ministry of Defence already faces unresolved technical and organisational questions over how to assure the safety, reliability and ethical operation of artificial intelligence in military systems.

BAE used the Farnborough International Airshow to unveil Brontanax, described by the company as the first British-designed autonomous Collaborative Combat Aircraft.

The uncrewed aircraft is intended to operate alongside piloted fighters, share intelligence, identify targets and increase frontline combat mass at a lower cost while retaining meaningful human command and control.

The concept envisages several uncrewed aircraft accompanying a conventional fighter, adding weapons, sensors and operational reach without replicating the full cost or complexity of a piloted platform.

BAE says Brontanax is designed to complement both existing aircraft and the next generation of combat systems rather than replace human crews altogether.

Woodburn rejected the idea that drones and autonomous platforms had made traditional military equipment obsolete.

Russia and other potential adversaries continue to build large aircraft, warships and submarines, he said, while supplementing them with uncrewed systems.

The effective model, in his assessment, combines expensive crewed platforms with numerous lower-cost autonomous assets.

His warning comes as senior military figures have openly questioned the readiness of Britain's armed forces.

First Sea Lord General Sir Gwyn Jenkins has acknowledged that the Royal Navy is not yet as prepared for war as it should be, while maintaining that it can conduct advanced operations and is working toward full warfighting readiness by the end of the decade.

His stated mission has been to move the service toward that condition over a four-year period.

The navy's condition has also attracted public criticism from the United States.

President Donald Trump described Britain's aircraft carriers as "toys," while US Defence Secretary Pete Hegseth mockingly referred to the "big, bad Royal Navy" during criticism of Britain's military contribution.

The delayed mobilisation of HMS Dragon to help protect Cyprus from Iranian and Hezbollah threats reinforced questions about response times and operational capacity.

Woodburn said BAE acted as soon as it received the required instruction from the Ministry of Defence.

"We get things in place as quickly as we're able to, but at the end of the day you need a signal to move," he said, placing responsibility for mobilisation decisions with the government rather than the contractor.

Britain's military capacity has contracted markedly since the end of the Cold War.

The regular Army numbered about 153,000 personnel in 1990; the present figure is approximately 74,000.

The expansion of remotely operated and autonomous systems may alter how many personnel future forces require, but those technologies also demand investment in secure communications, software, sensors, electronic warfare and industrial production.

The fiscal dispute has already reshaped the government.

Former defence secretary John Healey resigned after arguing that the funding allocated to the armed forces fell well short of what was required to protect the country.

An additional £13.5 billion was subsequently increased to £15 billion, but the revised settlement still left spending below the 3 percent of GDP Healey considered necessary by 2030.

New Prime Minister Andy Burnham appointed Healey as chancellor, a decision that lifted shares in major British defence companies.

BAE Systems rose 3.3 percent, while Babcock International, Rolls-Royce and QinetiQ also gained as investors anticipated stronger military expenditure under a Treasury led by a former defence secretary.

Woodburn welcomed the appointment, saying Healey understood the armed forces' requirements, while acknowledging that the chancellor would have to balance defence against intense demands from public services and strained national finances.

Burnham's pledge to increase defence spending comes as public debt exceeds 95 percent of GDP and long-term economic growth remains weak, sharply limiting the government's room for manoeuvre.

Defence Secretary Wes Streeting has nevertheless said military expenditure will receive priority over other departments.

Speaking at Farnborough, he argued that defence should be treated not merely as a recipient of economic growth but as a contributor to it, capable of supporting industrial renewal, advanced manufacturing and skilled employment in regions requiring greater investment.

Woodburn reinforced that economic case, saying the employment and industrial benefits of defence procurement must be explained clearly so the public understands why the money is being spent.

Research suggests that military spending can raise industrial employment and aggregate output, though its distributional effects and opportunity costs remain subjects of debate.

Asked whether he was troubled by producing weapons intended to kill, Woodburn said deterrence remained the central purpose.

"The best thing we can do is to deter," he said.

"Deterring war means our brave men and women have the best kit they could possibly have.

Our mission as a business is to protect those who protect us, and we take that incredibly seriously."

The immediate policy consequence is clear: Britain has committed itself to a much larger defence establishment without yet funding the full journey, while autonomous warfare is advancing faster than conventional procurement cycles.

Burnham's government must now translate its 2035 promise into budgets, production capacity and deployable forces capable of deterring the threats Woodburn says the country has underestimated.