Defence Secretary Michael Fallon was quick to attack the Labour leader, describing him as "dithering" and claiming he would "put Britain's security at risk". British voters head to the polls for a general election on June 8.
A leak on Thursday of Labour's draft manifesto featured on many of Friday's newspaper front pages, with the Sun describing it as "Labour's day of disasters" after a auto carrying Corbyn ran over a BBC cameraman's foot.
President Donald Trump is expected to sign an executive order on Thursday launching a commission to review alleged voter fraud and voter suppression in the US election system.
Turning his attention to Theresa May, he accused the Tory leader of "pandering" to the "erratic" Trump administration in the US.
Corbyn also said there would no more "hand holding" with US President Donald Trump - a reference to an embarrassing moment for Prime Minister Theresa May when the American leader took her by the hand during a visit to the White House.
Jeremy Corbyn has accused Theresa May of "pandering" to Donald Trump and warned she could embroil the United Kingdom military in Syria's civil war if returned to Downing Street.More news: Texas congressman calls for Trump's impeachment in impassioned speech on House floor
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Speaking at Chatham House in London, Mr Corbyn said: "I see it as the next Labour Government's task, as my task, to make the case for Britain to advance a security and foreign policy with integrity and human rights at its core". Corbyn said that he realized that military action may be necessary "as a last resort", but vowed to focus on defusing tensions.
Jeremy Corbyn will say he is "not a pacifist" and accepts that military action is needed "as a last resort" at a speech in London on Friday.
Recent U.K. governments, both Conservative and Labour, have joined US -led military interventions in Afghanistan, Iraq, Libya and against the Islamic State group in Syria. "The fact is that the "war on terror" which has driven these interventions has failed", he said.
The Tories have said they will not only retain the commitment to the North Atlantic Treaty Organisation target of spending 2% of GDP on defence - which Labour also supports - but also ensure there is an annual real-terms increase in the armed forces' budget throughout the next parliament.
May's Conservatives see Corbyn's opposition to military intervention and nuclear weapons as a major weakness to be exploited in the election campaign.
Corbyn said that a Labour government would seek greater worldwide cooperation to end the conflict in Syria and "work to halt the drift to confrontation with Russia. winding down tensions on the Russia-NATO border". The party's main slogan is "strong and stable" - in contrast to what May calls "a Corbyn-led coalition of chaos".