The UK's Northern Ireland Secretary Brandon Lewis is holding talks in Belfast on Monday to try and re-establish a devolved administration there after elections.
Sinn Féin, which wants to see Ireland and Northern Ireland unified, secured the most seats, a first for a nationalist party.
But the DUP, which wants Northern Ireland to remain part of the UK, is refusing to rejoin the Stormont executive until post-Brexit trading arrangements are changed.
Belfast journalist Amanda Ferguson says it's not clear if a power-sharing governmenment can be formed by the two parties.
IN: 'There's now...
OUT: ...crisis.'
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