She said the deal resolved the thorny language issue at the heart of the Stormont impasse with three separate pieces of legislation - an Irish Language Act, an Ulster Scots Act and an overarching Respecting Language and Diversity Act.
"The Good Friday Agreement was a landmark in U.S. Diplomacy; the devolved, power-sharing government of Northern Ireland a milestone achievement".
Sinn Fein accused the DUP of scuttling a deal at the last minute.
But Ms Villiers insisted the success of failure of negotiations "ultimately depends on Northern Ireland's leaders and in particular its two largest parties, the DUP and Sinn Fein".
Democratic Unionist Party leader Arlene Foster said the talks with the Irish Nationalist Shin-Fein Party to rebuild the government that broke up a year ago were unsuccessful.
Party negotiator Conor Murphy said: "If there's any possibility, however remote, of getting back to this engagement then we are obliged to try and explore that and we will do that and we will engage with the governments and the other parties in the coming period".
Foster, who as leader of the biggest party had been first minister, said that "despite our best efforts, serious and significant gaps" remained between the DUP and Sinn Fein over Irish language issues.
The surprise breakdown in talks came just two days after the British and Irish prime ministers visited Belfast and said the parties were close to a deal.
Smith said it was time for greater transparency if and when the talks between the parties resumed.
The British government faces the prospect of having to step in and take previously devolved decisions in Northern Ireland.
"Certainly there is no appetite to move toward direct rule (from London)".
As it stands Mrs Bradley is under a legal obligation to call another snap election in Northern Ireland but few observers see the merit in such an option, given it would likely return the same political make-up and not resolve any of the outstanding issues. They want that to be actioned through the British Irish Intergovernmental Conference - a peace process structure aimed at fostering cross-border co-operation between the governments.
"Those gaps were closed, that's why I don't understand (that) the commentary yesterday was as definitive as it was", Coveney said.
Ms McDonald said that at no stage was the Irish language going to be made compulsory in Northern Ireland or to apply quotas for Irish speakers to the public service.