When leading American figures such as former Congressmen Jim Walsh and Bruce Morrison, former U.S. special envoys to Northern Ireland Paula Dobriansky and Mitchell Reiss and former U.S. Ambassador Dan Rooney warn of a crisis in Northern Ireland then it is time to listen.

The five leaders and eight other leading luminaries in the fight for peace in Ireland issued a stiff letter this week, remarkable in its clarity on how badly the peace process is going.

What is particularly noticeable is the bipartisan nature of the letter. Republicans and Democrats agree on little, but the danger to the peace process is one they have come together on.

The alarm from America is well timed. For too long there has been a sense of leaving the issue of Northern Ireland to the leaders concerned with it back there on all sides.

But they seem incapable of moving forward. From issues to flags and emblems, marches, welfare payments to bread and butter issues on the economy, there is no agreement and complete stasis.

Currently the complete standstill means the dangers of a vacuum developing are very real.

Questions are being asked about the political future of Democratic Unionist Party (DUP) leader and the North’s First Minister Peter Robinson in particular, with much speculation that he will retire soon. He needs to proclaim what his future is sooner rather than later.

The protagonists, especially on the Unionist side, continue to proclaim that all is well. The Americans, however, think differently.

The facts are that without that original pressure and involvement of Bill Clinton, George Mitchell and the other leading Americas the peace process in Ireland would have foundered.

Now like the tolling bell in the distance, the Americans are warning again of deep trouble and making clear that the current stalemate is not good enough.

The major warning that “a stalemate without violence is still a stalemate” reflects a reality that, left long enough, a stalemate without violence could well become one with violence.

The call is for an immediate 30,000 feet view of the process and “how far it has come, how much remains unfinished and how much remains at risk.”

While praising Northern Ireland’s many achievements since the milestones of the Good Friday Agreement in 1998 and the establishment of the Stormont Executive in 2007, the letter raises the major concern that “compromise, the foundation of the agreement, has become almost impossible as the smallest issues go unresolved.”

This lack of willingness to compromise, says the letter, was the obstacle that prevented last year's all-party talks chaired by Haass and former State Department official Megan O'Sullivan from making any progress on the questions of flags, symbols, parades and the processes to resolve grievances from The Troubles.

“Children growing up without a vision of a shared cross-community future can too easily learn the ways of conflict again,” the letter cautions.

Let us hope the letter is taken seriously on all sides in Ireland and indeed in Britain. It was a monumental achievement to bring about peace in Ireland. Keeping it may be even harder.