"The reality today is that we have entered a new era, in which a fateful error—triggered by an accident, miscalculation, or blunder—could trigger a nuclear catastrophe… The Trump-Putin summit is an opportunity to stop this dangerous drift. Reaffirming that a nuclear war cannot be won and must never be fought, the United States and Russia could agree to specific steps at Helsinki to reduce nuclear risks," the letter read.
The tensions between Russia and NATO only heighten the risks of such a misstep, according to the letter.
READ MORE: Trump Told Putin to Ignore 'Stupid' White House Officials — Reports
The four authors suggested launching discussions about increasing the amount of time the US and Russian leaders have to decide on a course of action with regard to possible nuclear attacks from minutes to hours — or even days. By doing so, fatal mistakes can be avoided, and security in Europe and the United States can be ensured.
"A clear directive by the two presidents to their military leaders to work to develop options to achieve this goal would be a powerful signal to the American people, to the Russian people and to the world," the letter read.
Secondly, Putin and Trump are advised to launch talks on "reducing and managing cyber nuclear risks," to ensure that strategic nuclear facilities cannot be hacked.
"Third, work jointly to restart bilateral crisis management dialogue, including among uniformed military leaders in charge of nuclear forces, and multilateral crisis management dialogue throughout the Euro-Atlantic region, to reduce military risks," the letter said.
Additionally, Browne, Ischinger, Ivanov, and Nunn called on the two presidents to keep and extend existing disarmament agreements, such as Intermediate-Range Nuclear Forces (INF) Treaty and New START Treaty.
READ MORE: 'I Am Totally Prepared': Trump Expects to Have a Good Meeting With Putin
Finally, the open letter proposed to continue talks on "practical arrangements for the full and expeditious implementation of the commitments in the Singapore Summit Joint Statement."
The statement in question, signed by Trump and North Korean leader Kim Jong Un in June, reaffirms Pyongyang's commitment to denuclearize the Korean Peninsula.
Putin and Trump will meet in the Finnish capital on Monday.
