Iran and the United States have had no formal diplomatic relations since 1980. Pakistan serves as Iran's protecting power in the United States, while Switzerland serves as America's protecting power in Iran.

At one time when Shahanshah Reza Shah Pahlavi ruled the country, US and Iran relations were excellent. It was the 1979 Islamic revolution which brought an end to the dynasty of Pahlavi and western culture in Iran and brought forward Islamic culture including dress for men and women in the country to the forefront.

Iran and the US, after the Islamic revolution, look differently their foreign policies and no love lost between them. The US and Iran have gone separate ways. At one stage Iran called the US as "Satan"( evil) and that departed their ways.

Iran and US relations have deteriorated in recent times. It is reported that the US has bolstered economic sanctions and built up US military presence in the region accusing Iran of threats to US troops and interests. The US has not specified its threat from Iran.

Analysts believe that Trump could be lured into a conflict with Iran by the likes of US national security adviser John Bolton, an ardent Iran hawk.

As a follow up of worsening relations between the two nations, the Commander of the Iran's Revolutionary Guards named a new head of the force's intelligence unit on 18th May.

US President Donald Trump has issued a stern warning to Iran, suggesting it will be destroyed if a conflict breaks out between the two countries. "If Iran wants to fight, that will be the official end of Iran," he said in a tweet on 19th May.. "Never threaten the United States again!"

And when asked by reporters, the US President Donald Trump has issued a stern warning to Iran, suggesting it will be destroyed if a conflict breaks out between the two countries.

"If Iran wants to fight, that will be the official end of Iran," he said in a tweet on May 19. "Never threaten the United States again!"

The US has deployed additional warships and planes to the Gulf in recent days.

The latest frictions come after Iran suspended its commitments under the 2015 international nuclear deal, and threatened to resume production of enriched uranium which is used to make reactor fuel and nuclear weapons.

The deal aimed to cut sanctions on Iran in exchange for an end to its nuclear programme, but the US unilaterally withdrew from the agreement last year. Calling the deal "defective", Trump then re-imposed sanctions.

In recent days, the US has deployed the USS Abraham Lincoln aircraft carrier to the region and reportedly drawn up plans to send 120,000 troops to the Middle East.

Diplomatic staff have been reportedly ordered to leave Iraq, and the US military have raised the threat level in the region because of alleged intelligence about Iran-backed forces.

In a sign of heightened tensions across the region Exxon Mobil evacuated foreign staff from an oilfield in neighbouring Iraq after days of saber rattling between Washington and Tehran.

US officials are concerned that Tehran may have passed naval combat expertise onto proxy forces in the region. Tehran also had adopted new tactics and new destinations in shipping its oil exports. Iran's exports of oil reportedly have fallen in May to 500,000 barrels per day or lower, according to tanker data and industry sources, after the US tightened the screws on Iran's main source of income.

Elsewhere in the Gulf, Bahrain reportedly warned its citizens against travelling to Iraq or Iran due to "unstable conditions".

In the region there have been oil-tanker attacks, the US has pointed its fingers to Iran but Iranian officials reportedly denied its involvement in these attacks saying Tehran's enemies carried them out, preparing ground work for war against Iran.

Separately, Saudi Arabia accused Tehran of a drone attack on a pipeline on Friday. It alleged that Houthi rebels in Yemen conducted the strike on Iran's orders. A state-aligned Saudi newspaper called for the US to launch attacks on the country.

A senior Iranian legislator has called for the United States and Iran to hold talks in Iraq or Qatar to defuse tensions amid a US military build-up in the region.

Meanwhile Trump has also taken a softer approach towards Iran. Analysts say that President Trump's tweet marks a shift in tone after recent attempts to downplay the possibility of military conflict. Only a matter of days ago, the president told aides that he did not want US pressure on Iran to turn into a conflict.

It may be recalled that the main roots of tension between Iran and the United States in the post-9/11 Middle East. Since 9/11 and especially after the 2003 Iraqi crisis, Iran's role has sharply risen in the region. The evolution of Iran's role and power in the regional system has led Iran to seek a bigger weight and role more in tune with its acquired stature and capabilities.

The conflict between Iran and the United States has been generally attributed to either a political-ideological clash and mutual hatred, or to a simple aggregation of a number of distinct policy disputes including: Iran's nuclear program, Iran's state support for organizations that Washington regards as terrorist groups, human rights issues, and Iranian involvement in the new Iraq, the Levant, and Afghanistan. Some argue that the conflict, especially since 2003, has been essentially focused on a dispute over the growth of the two sides' role in Middle Eastern politics which both regard against each other's national interests and security.

The relations between the two nations are reportedly complex and interdependent nature of regional security necessitates, on the one hand, Iran's cooperation in the wake of the end of the U.S. combat role in Iraq in Summer 2010, and on the other, that the United States recognize and respect Iran's legitimate security concerns and accept the evolution of Iran's role in the region.

Barrister Harun ur Rashid, Former Bangladesh Ambassador to the UN, Geneva.