Northern Ireland Secretary of State James Brokenshire has called fresh Assembly elections, which will take place on Thursday March 2.
It comes after Sinn Fein collapsed the power-sharing institutions when they refused to nominate a deputy First Minister to replace Martin McGuinness, who resigned last Monday over the DUP's handling of the Renewable Heating Incentive scandal.
Sinn Fein said they would not "tolerate the arrogance and disrespect of the DUP".
Elections must be called if the positions at the top of the power-sharing executive remain vacant for seven days. The Assembly had until 5pm to come up with a solution to the impasse.
“I am now obliged, under relevant legislation, to propose a date for the next Northern Ireland Assembly election,” Mr Brokenshire said on Monday evening.
The last sitting day of the Assembly will take place on January 25 and the Assembly will be dissolved on January 26.
Mr Brokenshire urged political parties to “remain open to dialogue”.
"No-one should underestimate the challenge faced to the political institutions here in Northern Ireland and what is at stake,” Mr Brokenshire said.
“While it is inevitable that debate during an election period will be intense I would strongly encourage the political parties to conduct this election with a view to the future of Northern Ireland and re-establishing partnership government at the earliest opportunity after that poll."
"This is essential to the operation of devolved government and this means all must remain open to dialogue.
"The Government continues to stand firmly behind its commitment to the Belfast Agreement and its successes and our responsibilities to safeguard political stability here in Northern Ireland.
"We will continue to do all that we can to find a way forward to secure the continuation of devolved government."
Mr Brokenshire said he would make a further statement in Parliament on Tuesday.
Earlier, DUP leader Arlene Foster, who accepted her party's nomination as first minister, said the electorate did not want or need an election.
She accused Sinn Fein of triggering a poll because they did not like the outcome of last May's vote.
"They have forced an election that risks Northern Ireland's future and stability and which suits nobody but themselves," she said.
Mr McGuinness's move was precipitated by the Renewable Heat Incentive (RHI) scandal - a botched eco-scheme set to cost Stormont £490 million - but the row has also reignited a range of other disputes dividing the DUP/Sinn Fein-led coalition.