As Brexit negotiations between the U.K. and the EU loom, an imminent voting deal between Prime Minister Theresa May's Conservatives and 10 lawmakers from the Democratic Unionist Party (DUP) are casting a shadow over the hard-reached 1998 peace deal in Northern Ireland.
According to the Belfast Agreement, which largely ended decades of violence between Irish Catholic nationalists and pro-British Protestant unionists, the government in London must maintain a neutral stance between the opposing sides.
However, after losing its parliamentary majority in last Thursday's general election, the Conservative Party is now in talks for a so-called confidence and supply deal to act as a minority government backed by Northern Ireland's DUP.
The northern leader of the DUP's Sinn Fein opponents, Michelle O'Neill, recently said any deal between the Conservatives and the DUP will not last.
"This new arrangement between the DUP and the Tories will be transitory and will end in tears," she said during a speech in Londonderry, Northern Ireland's second city.
"But it will be the people of the north who will have to pay the price for the DUP's support for Brexit and for cuts."
Sinn Fein returned seven lawmakers in Thursday's general election but the party, because of its belief in a united Ireland, has never taken its seats in Westminster.
Party President Gerry Adams claimed a referendum on uniting the U.K. region with the Republic of Ireland is now "inevitable".
"One thing we can say for certainty; there is going to be a referendum on Irish unity," he added.
POLARIZATION
The 1998 multiparty deal stipulated there would be "rigorous impartiality" from London on any disputes in Northern Ireland.
However, the DUP's nascent deal with the Conservatives has prompted concerns over how the central U.K. government will be able to act as an honest broker in an administration propped up by 10 unionist lawmakers.
Northern Ireland is dominated by two main parties, the DUP and Sinn Fein. Both parties wiped out smaller rivals on Thursday, reflecting increasing polarization between Northern Ireland's two communities.
The local power-sharing administration collapsed earlier this year amid a Sinn Fein walkout caused by a multi-million-pound energy-scheme scandal and repeated clashes with the DUP over recognition of the Irish language, Troubles legacy issues and other disagreements.
A snap Northern Ireland election in March was ordered by the U.K.'s Northern Ireland Secretary James Brokenshire and saw Sinn Fein and the DUP returned as the largest parties from their respective communities.
The U.K. government has said June 29 is the deadline for finalizing talks to form a new Northern Ireland administration. Discussions will resume on Monday with representatives of the five main local parties.
Meanwhile, outgoing Irish Taoiseach (prime minister) Enda Kenny called Prime Minister Theresa May on Sunday, seeking assurances that "nothing should happen to put the Good Friday Agreement at risk".
May and Kenny had "confirmed their joint commitment to restoring the Northern Ireland executive as soon as possible," a U.K. government spokesman said.
"The prime minister reiterated that the government's approach and objectives in the forthcoming talks to re-establish the Northern Ireland executive remained unchanged," the statement added.
LARGEST UNIONIST PARTY
The DUP was founded in 1971 by hardline Protestant politician and clergyman Ian Paisley. For years it opposed any role for the Irish government in Northern Ireland and all peace deals between unionists and nationalists, including the Good Friday Agreement.
It later rose in strength to eclipse more moderate unionist rivals and is now the largest pro-British party in Northern Ireland, drawing support from many working-class Protestants and featuring a strong evangelical Christian base.
However, for a British government to be beholden to unionist lawmakers sets a dangerous precedent, according to some commentators.
Jonathan Powell, former chief of staff for Tony Blair's Labour government, which helped broker the 1998 peace deal, appealed to the Conservatives not to strike a deal with the unionists.
"As the main concern of the proposed DUP deal by the Conservatives is the impartiality of the central government in matters between the two sides of Northern Ireland, I spent 10 years doing the Northern Ireland peace negotiations… I really would appeal to the government not to go down this path," he told the broadcaster Sky News.
"[In] 1991, a Tory secretary of state said Britain would be neutral in Northern Ireland -- not take the side of the unionists, not take the side of the nationalists."
On social issues too, the DUP is facing opposition from voters in Britain, who are being confronted with the regional party's highly conservative worldview for the first time.
An online petition posted shortly after the deal's announcement on Saturday read: "Theresa May said there will NOT be a coalition of chaos."
It then cited a list of DUP positions outside the British mainstream: anti-gay rights, in favor of teaching creationism in schools, anti-abortion and calling for a return of the death penalty.
By Sunday lunchtime the petition had been signed by more than 650,000 people.
DONATION
Media attention has also focused on the source of an enormous donation made to the DUP in the run up to the June 2016 Brexit referendum which saw the U.K. decide to leave the EU.
A report in The Irish Times newspaper claimed a four-page DUP Leave advertisement in U.K. newspapers cost a staggering £282,000 ($360,000), paid out of a donation of £425,622 ($542,400) by a group called the Constitutional Research Council, headed by a Scottish conservative activist called Richard Cook.
This body has no apparent legal status or membership list, prompting queries as to how it could fund the DUP's huge advertising move.
The Irish Times article said the DUP did not reveal information on the large donation until February as Northern Irish political parties are governed by different funding rules to those in the rest of the U.K.
Party leader Arlene Foster later confirmed to the BBC that the Constitutional Research Council donated the money; party officials later said this explanation was enough and that they did not need to know the source of council's income.
The DUP has also drawn criticism over its perceived antipathy to Muslims. Former party leader Peter Robinson, who stood down in 2015, came under fire for standing by Belfast pastor James McConnell, who openly attacked Islam during a controversial sermon in 2014.
The evangelical Christian cleric provoked outrage when he described Islam as "heathen", "satanic" and "a doctrine spawned in hell".
McConnell said he did not trust Muslims. He apologized after charges were brought against him. He was acquitted in court after a judge found his remarks did not amount to being "grossly" offensive under the law.
Robinson compounded the controversy when, in a later interview he said: "I wouldn't trust Muslims devoted to Sharia law, but I would trust them to go down to the shops for me."
Questions are also swirling around senior DUP figures' involvement with quasi-paramilitary groups, particularly in the 1980s, such as Ulster Resistance.
