New START is a 10-year nuclear arms reduction treaty which was signed by the US and Russia in April 2010, and can be extended by up to five years following the ratification of both parties.
The treaty called for deployable nuclear warheads and bombs to be capped at no more than 1,550, the number of deployed missiles and bombers at 700, and the total number of deployed and non-deployed launchers at 800.
Speaking to Fox News following the Helsinki summit, the Russian leader revealed he reassured the US he was willing to extend the treaty.
He said: “I reassured President Trump that Russia stands ready to extend this treaty, to prolong it, but we have to agree on the specifics at first, because we have some questions for our American partners.
“We think that they are not fully compliant with the treaty, but this is for experts to decide.”
Both countries declared in February this year that the targets set within the treaty had been met.
However the Russian government has raised concerns over the US’s conversion of some of its nuclear submarines to carry conventional weapons.
They declared they had no way of verifying whether these adaptations had taken place.
The Trump administration has also regularly criticised the New START accord, with John Bolton, the President’s national security advisor, branding it “unilateral disarmament”.
The President also reportedly denounced the treaty during a phone-call with Mr Putin in 2017, calling it one of several bad deals negotiated by Barack Obama.
Following President Trump’s criticism of the programme, Democratic Senator Jeanne Shaheen denounced the US leader’s position on the treaty and declared it had helped keep the US safe.
She said: “It’s impossible to overstate the negligence of the President of the United States not knowing basic facts about nuclear policy and arms control.
“New START has unquestionably made our country safer, an opinion widely shared by national security experts on both sides of the aisle.”
Daryl Kimball, the executive director of the Arms Control Association, added: “Unfortunately, Mr Trump appears to be clueless about the value of this key nuclear risk reduction treaty and the unique dangers of nuclear weapons.”
Proponents of the accord have argued it has created a new monitoring regime which has allowed for both nations to verify compliance with the rules.
Former US Secretary of State Rex Tillerson also declared his support for the treaty during his Senate confirmation hearing in 2017.
He said: “It is important for the US to stay engaged with Russia, hold them accountable to commitments made under the New START and also ensure our accountability as well.”