Jeremy Corbyn was on the right side of history in supporting Irish republicans, Gerry Adams has said.
The Labour leader respected Sinn Fein's democratic mandate, the republican party's president added.
Mr Corbyn has said he wanted the bombings and shootings to stop but refused to single out the IRA for condemnation during recent interviews.
Mr Adams said: "Jeremy Corbyn was on the right side of history.
"What he did was very modest, what he did was very fundamental.
"He recognised the rights of the people who voted for Sinn Fein and I think he was vindicated by subsequent events.
"Because where he led - others followed."
Mr Corbyn and shadow chancellor John McDonnell have faced scrutiny over their association with Irish republicans.
Before the IRA ceasefire, they controversially met Sinn Fein a number of times in Westminster during the 1990s.
Mr Adams said the debate was a complete distraction and criticised Democratic Unionist leader Arlene Foster for intervening in it during a speech in London on Monday.
He added: "If Arlene Foster is lending herself to that complete distraction then she is trying to divert attention away from her party's support for an English Brexit, when she should be acknowledging the vote of the people here in the North and standing up for their rights."
Sinn Fein launched the party's General Election manifesto at a community centre in Dungannon, Co Tyrone.
Its leader in the north, Michelle O'Neill, said: "Jeremy Corbyn was someone who saw the primacy of dialogue, who engaged with Sinn Fein down through the years and respected our democratic mandate when others would not, so I think that his track record speaks for itself."
After becoming Labour leader in 2015, Mr Corbyn defended reaching out to republicans during the Troubles - insisting he "wanted the violence to stop".
Northern Ireland Secretary James Brokenshire has rounded on Mr Corbyn for his "IRA sympathies".
Mrs Foster has said he is beyond the political pale for his past support for republicans.