LONDON — Britain’s defense secretary has warned that the military may have to fight future wars without the help of the United States if the ally withdraws from leading Western defense.

"The assumptions of 2010 [Strategic Defence and Security Review] — that we were always going to be part of a U.S. coalition — is really just not where we are going to be,” Ben Wallace said in an interview with the Sunday Times on Jan 12.

Justifying Britain’s need to rethink how much it can rely on its key ally in the future, Wallace said: "Over the last year we’ve had the U.S. pull out from Syria, the statement by [U.S. President] Donald Trump on Iraq where he said NATO should take over and do more in the Middle East.”

The thought of the U.S. relinquishing its leadership role “keeps me awake at night," he said.

“It would be bad for the world and bad for us," he added. "We plan for the worst and hope for the best.”

The British government recently began a thorough review of the currently underfunded military, a move that could radically reshape the armed forces and their capabilities.

Wallace also used the interview to make a pitch for investment in capabilities.

“We are very dependent on American air cover and American intelligence, surveillance and reconnaissance assets. We need to diversify our assets,” he said.

Howard Wheeldon, of defense consultancy Wheeldon Strategic Advisory, said he admires the underlying tone of Wallace’s interview, affordability will remain a serious stumbling block.

“To believe that even if we have now raised our international ambitions and accepted the need for raised presence that, all of a sudden, we are going to reverse decades of scaling back defense capacity is quite frankly at odds with Downing Street and Treasury messaging," Wheeldon said. "Thus, whilst I might love the gist of a belief to be less reliant on others and spend more on developing what we believe we might need in the future, it will take a lot more convincing that what Mr. Wallace is attempting to say is merely anything more than an effort to balance what others are suggesting in the form of further defense cutbacks.”

The government plans to complete the defense review this year, possibly ahead of the governmentwide spending review timed for September. The spending review will likely focus on health and infrastructure projects in northern Britain rather than defense. Prime Minister Boris Johnson promised the defense review would be the most “radical reassessment” of Britain’s place in the word since the end of the Cold War.

Chief of the Defence Staff Gen. Nick Carter also recently weighed into the defense review debate. In a speech at the Royal United Services Institute think tank in London just before Christmas, Carter said the review must be upfront about the state of the military, noting government actions that have risked military readiness and resilience in the pursuit of efficiency.