THE great American writer Mark Twain was never a big fan of Jerusalem as a city. In his wonderful travel book The Innocents Abroad, he came to the conclusion that there would be no Second Coming there. Christ had been in Jerusalem once; he would not deign to come again, Twain concluded.

Twain’s irreverent reaction on visiting the city in 1867 epitomises the range of feelings so many have had about Jerusalem after spending time there. There is probably no city in the world that evokes such powerful emotions.

As someone who lived and worked as a journalist in the city on and off over many years, I felt my jaw drop and heart slump this week on hearing Donald Trump’s decision to recognise Jerusalem as Israel’s capital. As the news broke, I was instantly reminded of another quip made back in 2000 by Dennis Ross, former United States special envoy to the Middle East. On learning that controversial Israeli leader Ariel Sharon intended to go walkabout on the highly contentious religious site of what Jews call Temple Mount and Muslims call Haram al-Sharif in the heart of Jerusalem’s old city, Mr Ross’s response was unequivocal and succinct.

“I can think of a lot of bad ideas, but I can’t think of a worse one,” he said. And so it is with Mr Trump’s decision. Amid three catastrophic Middle East wars his announcement is a direct affront to peace efforts in the region.

Indeed, so rash is the move that not only does it beggar disbelief, but it also begs the question as to what could possibly have motivated Mr Trump to go through with it? On one level, it might simply be put down to his seemingly sociopathic tendency towards provocation, irrespective of the consequences or cost. The same goes for delivering on his presidential campaign promises to his home support base and to hell with the implications.

So many of Mr Trump the “deal” maker’s recent foreign policy moves that have outraged those outside the White House started with a campaign promise. But what a pathetic deal broker his Jerusalem decision has shown him to be.

Where are the political and diplomatic concessions he might have wrung from Israeli Prime Minister Benjamin Netanyahu for agreeing to recognise Jerusalem as Israel’s capital? Whether one agrees or not with Mr Trump’s move, was it not at the very least an ideal opportunity for him to insist that, in return for his capitulation, the Israelis needed to give a guarantee on halting all settlement building in the West Bank?

That in itself might possibly have breathed new life into the moribund peace process and reinvigorated hopes of a two-state solution instead of strangling it stone dead, as Mr Trump has done. There is a certain irony in the timing too of the decision, given that it was 100 years ago last month that the Balfour Declaration was signed. Not unlike Mr Trump’s latest move, it too imposed a unilateral understanding of the local reality without fully grasping its complex past and present. To this day ordinary Palestinians and Israelis have paid the price in blood.

Then again, what we have witnessed, some might say, is just another glaring example of Washington’s own seemingly “eternal and undivided” relationship with Israel and a US president dancing to Mr Netanyahu’s tune.

While living in Jerusalem, I would often stroll from Damascus Gate through the melee of bazaars in the Arab east of the old city. There the extent of the influence in the US by its pro-Israeli lobby was summed up by the slogan emblazoned across T-shirts on sale by Palestinian stallholders: “Don’t worry America, Israel is behind you”, the message sharply and ironically reassured Washington doubters beneath the diving silhouette of an Israeli F-16 fighter-bomber printed on the garments.

So influential is the pro-Israel lobby in America on the shape of Washington’s foreign policy that at times it’s difficult to tell just who is cracking the whip. One Israeli government source once explained away the extent of the lobby’s leverage this way.

“The Palestinians always complain that that we know the details of every proposal from the Americans before they do,” he remarked. “There’s good reason for that: we write them.” But Mr Trump’s Jerusalem foray is more than just another US president dancing to Israel’s tune. It has the capacity to ignite a powder keg at the heart of the Israel-Palestine conflict and the regional and international fallout that has so often run in tandem. Almost no sooner had Mr Trump made his announcement than one could sense panic in the US administration. Not only did a memo leak indicate that the US had privately asked Israel to temper its response to the announcement, but also another asked European officials to argue that Mr Trump’s decision did not prejudge the “final status” issue of Jerusalem’s sovereignty.

All of this is too little too late and the international condemnation is near universal, as it should be. But while the diplomatic outrage flares, the lasting toxic impact of Mr Trump’s decision will be on the city of Jerusalem and the 800,000 people who live there, 40 per cent of whom are Palestinian.

Ir Amim, or “City of Nations”, is a highly respected Israeli human rights group whose aim is to render Jerusalem a more equitable and sustainable city for Israelis and Palestinians. In its most recent report it points out that what Mr Trump has done is embolden Israeli policy makers pushing through a raft of bills and proposals aimed at unilaterally and decisively further redrawing the city’s boundaries and demographics.

These plans, says Ir Amim, have been transparently declared by some of their promoters as intended to render a two-state solution impossible. Therein perhaps lies the real reasoning behind Mr Trump’s willingness to lend Mr Netanyahu a hand. It was in the 10th century that the great Arab geographer Mohammed ibn Ahmad al-Muqaddasi once said that Jerusalem was “a golden basin filled with scorpions”.

Once again the city seems set to deliver a political sting that will be felt far beyond its walls and, doubtless, by Mr Trump himself.