Jeremy Corbyn has been coming under fresh attack from Conservatives after saying Labour's post-election defence review will consider the role of nuclear weapons.
His comments came in a TV interview hours after a controversial speech in which the Labour leader drew links between the UK's military interventions abroad and terrorism at home.
Theresa May accused Mr Corbyn of making excuses for terrorism in a way which showed he was "not up to the job" of being prime minister.
But a Labour spokesman said the Prime Minister was "not telling the truth" about Mr Corbyn's speech, in which he said Britain must be "both strong against terrorism and strong against the causes of terrorism".
Mr Corbyn's comments in a BBC1 interview with Andrew Neil threaten to reopen divisions within Labour over the nuclear deterrent, after he voted against Trident renewal last year despite party policy to maintain the system.
The Labour leader seven times declined to say that he supported the deterrent, though he said the party's policy in favour of renewal would be implemented if he became PM.
"I voted against the renewal," said Mr Corbyn. "Everybody knows that because I wanted to go in a different direction. That is the decision that's been taken. I respect that decision going ahead.
"We're going ahead with the programme which has been agreed by Parliament and voted on by the Labour Party."
But he suggested the role of nuclear weapons would be up for consideration in the strategic defence review planned if Labour wins office.
"It will look at the role of nuclear weapons as it will look at everything," he said.
Mr Corbyn's comments fall well short of shadow foreign secretary Emily Thornberry's suggestion that the review might reopen the issue of whether to renew the deterrent, which earned her a slapdown from shadow defence secretary and Trident supporter Nia Griffith.
But they are likely to be seized upon by his opponents as a further sign of a lack of personal commitment to the nuclear deterrent, especially as the Labour leader stressed his support for "a nuclear-free world through multilateral disarmament through the Nuclear Non-proliferation Treaty".
Ms Griffith later said Mr Corbyn had made clear the defence review "would not question whether or not we would go ahead with the renewal of Trident".
But asked whether there was any merit in having nuclear weapons if Mr Corbyn said he would never use them, she told BBC Radio 4's Any Questions: "If it is a deterrent, then you do have to be prepared to use it."
And Ms Griffith indicated she did not believe in the link her leader drew between British interventions abroad and terror at home, telling the programme: "The terrorist ideology we are dealing with hates us even before we have taken part in any such action."
Mr Corbyn promised to be a "committed" member of Nato as prime minister and told Andrew Neil he would not talk to the Islamic State terror group. And he insisted he had never met members of the IRA and did not support them.
But Conservative International Development Secretary Priti Patel said: "The fact is he backed the IRA, doesn't support Nato, wouldn't renew Trident, wants to increase immigration and wants to massively increase taxes on working families.
"In two weeks' time there is a choice. Either Jeremy Corbyn negotiating Brexit just 11 days after the election, or Theresa May. Brexit is central to everything - a vote for anyone other than Theresa May puts Corbyn in Downing Street and everything at risk."
Mr Corbyn was due on Saturday to watch his beloved red-shirted Arsenal take on the blues of Chelsea in the FA Cup Final at Wembley.
Mrs May was expected to concentrate on the ongoing investigation into the Manchester bombing, chairing a meeting of the Government's Cobra emergency committee, while Liberal Democrat leader Tim Farron is in his Cumbria constituency.