Jeremy Corbyn would end airstrikes in Syria, not use nuclear weapons and seek to build a closer relationship with Russian President Vladimir Putin if elected Britain's next prime minister.
The Labour leader also said he would avoid using drone strikes, even if it meant killing Isis leader Abu Bakr al-Baghdadi, in a wide-ranging interview on the BBC's The Andrew Marr Show.
Corbyn was asked to clarify a number of his foreign policy views on Sunday (23 April) as he hoped to convince the country he should be its next leader ahead of the 8 June election.
On nuclear weapons, Corbyn said: "I have made clear my views on nuclear weapons. I have made clear that there would be no first use of it. I have made clear that any use of nuclear weapons is a disaster for the whole world.
"I think we should look at the process by which we achieve peace and security because, actually, nuclear weapons are not the solution to the world's security issues, they are the disaster of the world's security issues if ever used."
In January, the Bulletin of Atomic Scientists moved the Doomsday Clock 30 seconds closer to midnight, signifying a greater probability of joint nuclear destruction.
On the issue of Trident, Corbyn said his party has not decided whether it will scrap the programme, but will reach a conclusion shortly before the Labour manifesto is released in early May. Corbyn has long been an advocate of scrapping the nuclear deterrent but faces resistance in his party on this policy.
"We will have a strategic defence review immediately which will include all aspects of defence, as most incoming governments do," Corbyn said when asked if he would cancel Trident.
"We would then look at the situation at that time, but we would also make sure our armed forces are properly funded and our armed forces are able to play their part in peacekeeping around the world."
A report by the Sunday Times in January revealed there was a Trident misfire weeks before parliament last voted on the issue, but the information was withheld from MPs. Prime Minister Theresa May was then accused of purposefully misleading MPs but declined to answer why the misfire was not disclosed.
When asked by Marr if he would authorise a drone strike on al-Baghdadi if intelligence officials believed they knew where he was, Corbyn said: "What I would tell them is give me the information you have got, tell me how accurate that is and tell me what you think can be achieved."
He continued: "What is the objective here? Is the objective to start more strikes that may kill many innocent people as has happened or is the objective to get a political solution in Syria?
"My whole point would be, does this help to get a political solution in Syria?"
When pressed on whether he believed killing al-Baghdadi would help deliver a political solution, Corbyn said: "I think the leader of Isis not being around would be helpful and I'm no supporter or defender in any whatsoever of Isis, I'm sure you would concede, but I would also argue that the bombing campaign has killed a large number of civilians, many of whom were virtually prisoners of Isis, you have got to think about these things."
Independent monitoring group Airwars has recorded at least 3,000 deaths of innocent civilians in Syria and Iraq since the Coalition's airstrikes against Isis began.
Last week, the organisation said civilians killed in airstrikes were now dying at a rate faster than any time before.
The Labour leader added: "At the end of the day the only solution in Syria is going to be a political one. There is no other way of getting it. There has to be a reconvening quickly of the Geneva process.
"I would say to President [Donald] Trump, 'Listen, it's in nobody's interest for this war to continue. Let's get the Geneva process going quickly and in the meantime, no more strikes.
"Have the UN investigation into the war crime of the use of chemical weapons in Syria and take it on from there.'"
He added: "I want us to say, 'Listen, let's get people around the table quickly and a way of achieving that is to suspend the strikes.'"