Wikimedia Commons
A Trident II (D-5) missile underwater launch.
The ex-Labour minister, who was Defence Secretary between 2006 and 2008, said "weak spots" in Trident need to be addressed - otherwise Prime Minister David Cameron won't be able to rely on the nuclear deterrent "when he needs to reach for it."
Trident, the UK's nuclear programme, consists of four Vanguard-class submarines armed with Trident II D-5 ballistic missiles. It is the most powerful capability of the British military forces but at £31 billion it's also the most expensive.
Lord Browne told BBC political editor Laura Kuenssberg that the Tory government has an "obligation" to assure MPs that all aspects of Trident have been assessed against the risk of a cyber attack and that the appropriate security measures were in place.
"If they are unable to do that then there is no guarantee that we will have a reliable deterrent or the prime minister will be able to use this system when he needs to reach for it," he added.
However, former Conservative Defence Secretary Sir Malcolm Rifkind downplayed the risk of Trident becoming obsolete.
"The whole point of our nuclear weapons is not whether they would work - 100% guarantee - if they were ever required," he told the BBC. "You think they will do.
"The question is whether an enemy contemplating aggression would be prepared to take the risk."
Lord Browne has campaigned against the proliferation of nuclear weapons throughout his political career through organisations such as the Nuclear Threat Initiative, of which he is vice chairman, and the European Leadership Network for Multilateral Nuclear Disarmament and Non-proliferation.
Jeremy Corbyn, leader of the Labour Party, is against Trident and wants Labour to renew its stance on the nuclear deterrent. He's currently trying to convince Labour MPs to abstain from the upcoming vote in the House of Commons.