In coded diplomatic missives, in messages sent through intermediaries and in statements from their leaders, both Iran and the United States have signalled their desire to step back from a confrontation that had sparked fears of a wider conflict – at least for now.

But the events of the past week have dashed any small hope of diplomacy that might have eased tensions between the two enemies.

The killing of top Iranian general Qassem Soleimani by the US, and Iran’s retaliatory missile strikes on American bases in Iraq have piled the pressure on a landmark 2015 nuclear deal between Tehran and world powers, which the international community had largely agreed was working.

In what was billed as an overture intended to de-escalate tensions, the US said on Wednesday it was ready to engage in “serious negotiations” with Iran.

In a letter to the United Nations Security Council, ambassador Kelly Craft said the US was ready to talk “without preconditions”, with the aim of “preventing further endangerment of international peace and security or escalation by the Iranian regime”.

Qassem Soleimani: Mourners fill Iran streets for funeral Show all 24 1 /24 Qassem Soleimani: Mourners fill Iran streets for funeral Qassem Soleimani: Mourners fill Iran streets for funeral Kerman - Final stage of funeral processions Iranian mourners gather around a vehicle carrying the coffin of top general Qasem Soleimani during the final stage of funeral processions, in his hometown Kerman. Soleimani was killed outside Baghdad airport in a drone strike ordered by US President Donald Trump, ratcheting up tensions with Iran which has vowed "severe revenge" AFP via Getty Images Qassem Soleimani: Mourners fill Iran streets for funeral Tehran Iranian people carry a coffin of Iranian Major-General Qassem Soleimani during a funeral procession in Tehran Official Khamenei website via Reuters Qassem Soleimani: Mourners fill Iran streets for funeral Kerman - Final stage of funeral processions The assassination of the 62-year-old heightened international concern about a new war in the volatile, oil-rich Middle East and rattled financial markets AFP via Getty Qassem Soleimani: Mourners fill Iran streets for funeral Kerman - Final stage of funeral processions Iranian people attend a funeral procession and burial for Iranian Major-General Qassem Soleimani, head of the elite Quds Force, who was killed in an air strike at Baghdad airport, at his hometown in Kerman, Iran January 7, 2020. Mehdi Bolourian/Fars News Agency/WANA (West Asia News Agency) via REUTERS ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY WANA NEWS AGENCY West Asia News Agency via Reuters Qassem Soleimani: Mourners fill Iran streets for funeral Tehran Mourners packed the streets of Tehran for ceremonies to pay homage to Soleimani, who spearheaded Iran's Middle East operations as commander of the Revolutionary Guards' Quds Force and was killed in a US drone strike on January 3 Iranian Supreme Leader's Office/EPA Qassem Soleimani: Mourners fill Iran streets for funeral Kerman - Final stage of funeral processions Iranian mourners gather around a vehicle carrying the coffin of slain top general Qasem Soleimani during the final stage of funeral processions, in his hometown Kerman on January 7, 2020. - Soleimani was killed outside Baghdad airport Friday in a drone strike ordered by US President Donald Trump, ratcheting up tensions with arch-enemy Iran which has vowed "severe revenge". The assassination of the 62-year-old heightened international concern about a new war in the volatile, oil-rich Middle East and rattled financial markets. (Photo by ATTA KENARE / AFP) (Photo by ATTA KENARE/AFP via Getty Images) ATTA KENARE AFP via Getty Images Qassem Soleimani: Mourners fill Iran streets for funeral Tehran Iranians set a US and an Israeli flag on fire during the funeral procession AFP via Getty Images Qassem Soleimani: Mourners fill Iran streets for funeral Tehran Iran's Supreme Leader Ayatollah Ali Khamenei, centre, with Parliament Speaker Ali Larijani, second left, and President Hassan Rouhani, third left, standing next to him as he leads a prayer over the caskets of Iranian military commander Qasem Soleimani and Iraqi paramilitary chief Abu Mahdi al-Muhandis at Tehran University Khamenei.IR/AFP via Getty Qassem Soleimani: Mourners fill Iran streets for funeral Kerman - Final stage of funeral processions Mourners attend a funeral ceremony for Iranian Gen. Qassem Soleimani and his comrades, who were killed in Iraq in a U.S. drone strike on Friday, in the city of Kerman, Iran, Tuesday, Jan. 7, 2020. The leader of Iran's Revolutionary Guard threatened on Tuesday to "set ablaze" places supported by the United States over the killing of a top Iranian general in a U.S. airstrike last week, sparking cries from the crowd of supporters of "Death to Israel!" (Erfan Kouchari/Tasnim News Agency via AP) Erfan Kouchari AP Qassem Soleimani: Mourners fill Iran streets for funeral Tehran Iranian Supreme Leader Ayatollah Ali Khamenei, left, openly weeps as he leads a prayer over the coffin of Qassem Soleimani AP Qassem Soleimani: Mourners fill Iran streets for funeral Tehran Mourners holding posters of Qassem Soleimani AP Qassem Soleimani: Mourners fill Iran streets for funeral Tehran Coffins of Soleimani and others who were killed in Iraq by a US drone strike, are carried on a truck surrounded by mourners during a funeral procession, at the Enqelab-e-Eslami (Islamic Revolution) square AP Qassem Soleimani: Mourners fill Iran streets for funeral Kerman - Final stage of funeral processions An Iranian mourner holds a placard AFP via Getty Images Qassem Soleimani: Mourners fill Iran streets for funeral Tehran Downtown Tehran was brought to a standstill as mourners flooded the Iranian capital Khamenei.IR/AFP via Getty Qassem Soleimani: Mourners fill Iran streets for funeral Tehran Former Iranian Revolutionary Guards Corps chief Mohamad Ali Jafari prays on the coffins of Qasem Soleimani and of other victims during their funeral ceremony EPA Qassem Soleimani: Mourners fill Iran streets for funeral Kerman - Final stage of funeral processions Iranian mourners gather during the final stage of funeral processions for slain top general Qasem Soleimani, in his hometown Kerman on January 7, 2020. - Soleimani was killed outside Baghdad airport on January 3 in a drone strike ordered by US President Donald Trump, ratcheting up tensions with arch-enemy Iran which has vowed "severe revenge". The assassination of the 62-year-old heightened international concern about a new war in the volatile, oil-rich Middle East and rattled financial markets. (Photo by ATTA KENARE / AFP) (Photo by ATTA KENARE/AFP via Getty Images) ATTA KENARE AFP via Getty Images Qassem Soleimani: Mourners fill Iran streets for funeral Tehran epa08107653 Iranians attend the funeral ceremony of slain Iranian Revolutionary Guards Corps (IRGC) Lieutenant general and commander of the Quds Force Qasem Soleimani and of other victims in Tehran, Iran, 06 January 2020. Soleimani was killed in a targeted US airstrike on 03 January 2020 in Baghdad, Iraq. EPA/ABEDIN TAHERKENAREH ABEDIN TAHERKENAREH EPA Qassem Soleimani: Mourners fill Iran streets for funeral Tehran epa08107308 A handout photo made available by Iranian Supreme Leader's Office shows Iranian Supreme Leader Ayatollah Ali Khamenei (C) praying before the coffins of slain Iranian Revolutionary Guards Corps (IRGC) Lieutenant general and commander of the Quds Force Qasem Soleimani and of other victims as Iranian President Hassan Rouhani (C-L) and other top officials attend the funeral ceremony in Tehran, Iran, 06 January 2020. Soleimani was killed in a targeted US airstrike on 03 January 2020 in Baghdad, Iraq. EPA/IRAN'S SUPREME LEADER OFFICE HANDOUT HANDOUT EDITORIAL USE ONLY/NO SALES IRAN'S SUPREME LEADER OFFICE HANDOUT EPA Qassem Soleimani: Mourners fill Iran streets for funeral Kerman - Final stage of funeral processions Women hold pictures of Iranian Major-General Qassem Soleimani, head of the elite Quds Force, who was killed in an air strike at Baghdad airport, during a funeral procession and burial at his hometown in Kerman, Iran January 7, 2020. Mehdi Bolourian/Fars News Agency/WANA (West Asia News Agency) via REUTERS ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY WANA NEWS AGENCY West Asia News Agency via Reuters Qassem Soleimani: Mourners fill Iran streets for funeral Tehran Iranian people gather during a funeral for Iranian Major-General Qassem Soleimani, head of the elite Quds Force, and Iraqi militia commander Abu Mahdi al-Muhandis, who were killed in an air strike at Baghdad airport, in Tehran, Iran January 6, 2020. Official Khamenei website/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. NO RESALES. NO ARCHIVES Official Khamenei website Official Khamenei website via Reuters Qassem Soleimani: Mourners fill Iran streets for funeral Kerman - Final stage of funeral processions Iranian mourners gather during the final stage of funeral processions for slain top general Qasem Soleimani, in his hometown Kerman on January 7, 2020. - Soleimani was killed outside Baghdad airport on January 3 in a drone strike ordered by US President Donald Trump, ratcheting up tensions with arch-enemy Iran which has vowed "severe revenge". The assassination of the 62-year-old heightened international concern about a new war in the volatile, oil-rich Middle East and rattled financial markets. (Photo by ATTA KENARE / AFP) (Photo by ATTA KENARE/AFP via Getty Images) ATTA KENARE AFP via Getty Images Qassem Soleimani: Mourners fill Iran streets for funeral Kerman - Final stage of funeral processions Men hold pictures of Iranian Major-General Qassem Soleimani, head of the elite Quds Force, who was killed in an air strike at Baghdad airport, during a funeral procession and burial at his hometown in Kerman, Iran January 7, 2020. Mehdi Bolourian/Fars News Agency/WANA (West Asia News Agency) via REUTERS ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY WANA NEWS AGENCY West Asia News Agency via Reuters Qassem Soleimani: Mourners fill Iran streets for funeral Tehran This Monday, Jan. 6, 2020 satellite photo from Maxar Technologies shows Enghelab Square in Tehran, Iran, amid a mass processional for Iranian Gen. Qassem Soleimani, who was killed in a U.S. airstrike in Baghdad. The funeral for Soleimani drew a crowd said by police to be in the millions in the Iranian capital, filling thoroughfares and side streets as far as the eye could see. Although there was no independent estimate, aerial footage and Associated Press journalists suggested a turnout of at least 1 million. (Satellite image Â©2020 Maxar Technologies via AP) Satellite image Maxar Technologies/AP Qassem Soleimani: Mourners fill Iran streets for funeral Tehran epa08107478 Iranians attend the funeral ceremony of slain Iranian Revolutionary Guards Corps (IRGC) Lieutenant general and commander of the Quds Force Qasem Soleimani and of other victims in Tehran, Iran, 06 January 2020. Soleimani was killed in a targeted US airstrike on 03 January 2020 in Baghdad, Iraq. EPA/ABEDIN TAHERKENAREH ABEDIN TAHERKENAREH EPA

It came hours after similar remarks by Donald Trump in his first public address since ordering the assassination of Soleimani, the leader of Iran’s Quds Force, a week ago.

“We must all work together toward making a deal with Iran that makes the world a safer and more peaceful place,” the president said, while blaming the 2015 nuclear deal for emboldening Iran in the Middle East.

But many were quick to cast doubt on the sincerity of his calls for talks, delivered in a speech in which he announced the US would be imposing “additional punishing sanctions” on Iran.

Tehran sharply dismissed the possibility, citing the killing of Soleimani and crippling US sanctions on the Iranian economy. Majid Takht Ravanchi, Iran’s ambassador to the UN, called the suggestion of new talks “unbelievable”, Iran’s state news agency IRNA has reported.

In what appeared to be Iran’s first official reaction to Mr Trump’s address, he was quoted as saying Washington had “initiated a new series of escalation and animosity with Iran” by killing Soleimani.

“As long as the US continues its hostilities, the talk of cooperation is not comprehensible and the Iranian people will not be deceived by such remarks,” he said.

Analysts, too, suggested that negotiations may not be a priority for Washington now.

Aaron David Miller, a former State Department analyst and negotiator in Democratic and Republican administrations and senior fellow at the Carnegie Endowment for International Peace, described Mr Trump’s speech as “a combination of crowing, accusing and explicit threats plus more sanctions. This is a speech for continued confrontation. And the message to the regime is change or else.”

“Even by reading tea leaves, coffee grinds and goat entrails, it’s hard to identify in Trump’s speech any trace of serious intention to negotiate with Iran. Only in America does the pendulum among the chattering classes go from World War Three to negotiations,” he said.

Mr Miller told The Independent that ​serious negotiations “require an enormous investment and a team of individuals who know what they are doing,” which the Trump administration has not put together.

Despite publicly showing a willingness for reconciliation, there appears to be little sign of a departure from the administration’s “maximum pressure” approach intended at forcing Iran back to the negotiating table.

Ali Vaez, director of the Iran Project at the International Crisis Group, said the “door to diplomacy has been shut for now”.

“There is no way that [Iranian] president [Hassan] Rouhani would meet with his American counterpart who ordered Soleimani’s assassination. And without the pageantry of a summit, Trump seems uninterested in dealing with Tehran,” he told The Independent.

What happens to the 2015 nuclear deal now, formerly known as the Joint Comprehensive Plan of Action (JCPOA) is unclear. Mr Trump pulled the US out of the agreement in 2018, despite US allies insisting that it was succeeding in its primary purpose of halting Iran’s ability to acquire nuclear weapons. That move was seen as the starting point of escalating tensions between the Trump administration and Iran, which reached a crescendo this week.

The Trump administration has repeatedly called on other world powers who signed up to the deal to also abandon it, and Mr Trump did so again on Wednesday.

“The time has come for the United Kingdom, Germany, France, Russia and China to recognise this reality. They must now break away from the remnants of the Iran deal,” he said.

Vice-president Mike Pence doubled down on those remarks on Thursday.

“The president is going to call on our allies, in the days ahead, to join the United States to withdraw from the disastrous Iran nuclear deal and demand that Iran abandon its long history of sowing terrorist violence, abandon its nuclear ambitions and join the family of nations,” he said in an interview on Fox & Friends.

European powers have resisted such calls, however. Boris Johnson distanced the UK from its transatlantic ally on Thursday in a phone call with Iran’s president.

Mr Johnson’s spokesman said the prime minister “underlined the UK’s continued commitment to the [deal] and to ongoing dialogue to avoid nuclear proliferation and reduce tensions”.

The 2015 deal gave Iran sanctions relief in return for imposing restrictions on its nuclear programme. But the sanctions imposed on Tehran by Washington since the US abandoned the deal have led to Iran taking its own steps to withdraw from parts of the deal.

And in the aftermath of Soleimani’s killing, Iran announced that it will roll back its commitments even further, among them restrictions on the number of centrifuges it could operate and the level of uranium enrichment.

“The JCPOA has been in a coma since the US withdrawal from the nuclear agreement,” said Holly Dagres, a non-resident fellow specialising on Iran at the Atlantic Council think-tank.​

“Having said that, it’s not dead. Iran has repeatedly said it would return to aspects of the JCPOA if the US lifts sanctions and/or returns to the deal.”

But, she added, the chances of that happening are slim.

“I don’t find the US calls for negotiations to be genuine, given that the Trump administration has continuously changed its preconditions,” she told The Independent.