In the headline-grabbing drama of US president versus UK ambassador, one plot point has largely escaped attention: Donald Trump’s first ‘disinviting’ of Kim Darroch was the diplomat’s exclusion from a White House reception on Monday for the visiting ruler of Qatar, Emir Sheikh Tamim bin Hamad Al Thani.

The dinner itself was heavily trade-oriented, with some forty US business leaders invited as well as some diplomats. Its significance, however, lies in the considerable welcome given to Thani while several close allies of the US – Saudi Arabia, the United Arab Emirates, Egypt and Bahrain – are blockading his country.

Rivalry between the Saudi and Qatari royal families goes back many years but came to a head more than two years ago when the Saudis accused Qatar of supporting terrorism. This escalated to the blockade which has held since June 2017, making Trump’s welcome for Thani this week complicated, to say the least. A further difficulty for the US is the diplomatic relations that Qatar maintains with Iran, which is the enemy of Saudi Arabia, the Emirates and, of course, of Trump himself.

The charge of helping terrorism should be taken with a pinch of salt. Qatar certainly has opened a diplomatic door to the Taliban, but its support for radical Islamist paramilitaries is highly variable. What is more, Saudi Arabia faces similar allegations itself. For decades it has backed madrasas inclined to its own conservative version of Islam right across the Middle East and South Asia, and there are frequent claims that these schools have provided a useful environment for extreme groups such as al-Qaida and ISIS to recruit young believers.

A bigger problem is Al Jazeera. The Saudis dislike intensely this Qatari-backed media network and the critical reports on Middle Eastern autocracies that it broadcasts. They are also unhappy at Doha’s streak of independence in its overall diplomatic relations, which includes occasional support for Hamas. Equally unwelcome is Qatari support for Government of National Accord in Libya against the rebel Libyan National Army. The UN backs the Government of National Accord too, but Egypt, Saudi Arabia and the UAE have lent the rebels considerable support in the belief that they can suppress any upsurge in support for ISIS.

Given the power of those blockading Qatar, how is that the state is surviving and indeed thriving? There are three main reasons. One is that Qatar is immensely rich, thanks to its huge natural gas reserves: under the Gulf between Qatar and Iran lies the world’s largest gas field, the North Shore/South Pars reservoir. This single field contains nearly 30% of the planet’s recoverable reserves. It is shared with Iran, which is why it is sensible for Qatar to maintain reasonable relations with Tehran whatever the views of the Saudis and others.

The second reason is that Qatar hosts the most important US base in the Middle East at Al Udeid. Constructed twenty years ago, the base houses 10,000 US troops as well as the forward HQ for US Central Command, which controls forces right across the Middle East.

One of many ironies is that the Pentagon has recently deployed a squadron of F-22 stealth fighters to Al Udeid with the specific purpose of strengthening its capabilities against Iran, yet Qatar is Iran’s sole ally among western Gulf states. Another irony is that the head of US Central Command Air Forces when Al Udeid was first built, General Charles Ward, is now arguing that Trump should threaten to close the base and withdraw from Qatar because of its ties with Iran.

In all this complexity there remains the question of why the emir got such a welcome from Trump earlier this week, even though John Bolton, Mike Pompeo and Mike Pence, respectively Trump’s national security adviser, secretary of state and vice-president, and all Iran hawks, would have given it through gritted teeth. Trump himself was quick to explain, which brings us to the third reason. “They are investing very heavily in our country,” the president said. “They’re creating lots of jobs. They’re buying tremendous amounts of military equipment, including planes.” For Trump the bottom line is the bottom line: money, and specifically trade. Boeing, Raytheon, General Electric, Gulfstream and Chevron are all signing contracts collectively reported to be worth many billions of dollars, on top of an existing economic partnership valued at $185 billion.

Still it is possible that the relationship between Doha and Washington might come to have a rather different value. This is because there is cause for some guarded optimism over the US-Iran confrontation even as we saw on Wednesday the near-clash between the British frigate HMS Montrose and some Iranian Revolutionary Guard patrol craft.

It is becoming clear that many in the Pentagon are not welcoming the slide to war and even some close confidants of Trump are urging caution. This is where the Qatari leadership may have a role: it could be a useful interlocutor in any improvement in relations, even to the extent of tentative diplomatic explorations of a possible compromise. It might be wishful thinking, but Qatar is a singularly rich country and the language of money is one that Trump, of all people, speaks with enthusiasm.