Former Defence Secretary Sir Michael Fallon says Russia is "clearly a threat" to the UK and other democracies in western Europe.
Speaking to Forces News just a day before he is due to step down as an MP, Mr Fallon said the UK "should never underestimate" Russia.
It comes after the news that a report on alleged Russian interference on the 2016 EU referendum would not be released until after December's election.
"If you told me 10 years ago that Russia would try and influence an American Presidential election or try and influence a referendum in the Netherlands or Russia would intervene in the Balkans, in Montenegro, in the way that it tried - I simply wouldn't have believed it possible," Mr Fallon said.
"We should never underestimate Russia's capacity for causing trouble, for intervening, for messing up the democratic process.
"It's wholly possible that Russia could try and intervene [in the upcoming election] but again, I just think people are a bit wiser to it than they were a few years ago."
The Tory MP spent three-and-a-half years as Defence Secretary between 2014 and 2017.
He oversaw the end of combat operations in Afghanistan, the start of Operation Shader and airstrikes in Syria.
The Sevenoaks MP said there was an "awful lot to get to grips with" when arriving at the Ministry of Defence.
But his time as Defence Secretary ended in controversy.
He resigned from the role following allegations he touched a journalist's knee.
"I think that particular incident was rather a long time ago but there you are, that's politics," Mr Fallon said.
He added: "I was in no doubt it was right to resign.
"I was championing a code of conduct for the Armed Forces and it's right that the Secretary of State should be held to the highest account."
As Brexit dominates much of the debate around the forthcoming General Election, Mr Fallon still has his concerns.
He campaigned for Remain in the 2016 EU referendum and said he is worried by the potential security consequences of Brexit.
"I have the same concerns I had during the referendum," he said.
"The security partnership we have with the European Union is important.
"There simply has to be cooperation between our police forces, our courts hear and between our armed forces.
"Now, that's been delayed because of the long wrangle over the withdrawal agreement but the security agreement I hope can be put in place very quickly next year to make sure there isn't a gap in our security arrangements."
Mr Fallon has spent 31 years as a Conservative MP, representing Darlington and Sevenoaks in that time, the latter a seat he has held since 1997.
The 67-year-old is just one of more than 50 MPs stepping down, including defence minister Mark Lancaster and Speaker John Bercow.
Mr Fallon said he will leave Westminster with "particular memories of defence" and the "wonderful people" of the Armed Forces.