DUBAI, United Arab Emirates (AP) — Just two days after banning travellers from seven Muslim-majority nations, US President Donald Trump invited the Saudi monarch, whose kingdom includes Islam’s holiest sites, to fly to Washington.

It points to the delicate balancing act Trump faces as he tries to deliver on campaign promises to exterminate “radical Islamic terrorism” without endangering political and economic ties with US allies in the region, including some where the Trump Organization has business interests.

The executive order could upend gains on the battlefields of Mosul, where US forces aid Iraqi commandos, or scuttle billions of dollars’ worth of American aircraft sales to Tehran. Trump has vigorously defended the ban, saying it is only “about terror and keeping our country safe”.

Traditional American allies in the region have kept largely silent about the ban. Many welcome tougher action against Iran, one of the seven countries included in the executive order. But any move to expand the ban to other countries will undoubtedly inflame public opinion and could force them to respond in kind.

“Such selective and discriminatory acts will only serve to embolden the radical narratives of extremists and will provide further fuel to the advocates of violence and terrorism at a critical time,” the Organization of Islamic Cooperation said yesterday.

The 57-nation bloc urged the US to reconsider the policy “and maintain its moral obligation to provide leadership and hope at a time of great uncertainty and unrest in the world”.

The warning came hours after Trump called Saudi King Salman and Abu Dhabi’s powerful crown prince, Sheikh Mohamed bin Zayed Al Nahyan, the likely future president of the United Arab Emirates. King Salman also invited Trump to visit Saudi Arabia.

Official regional government reaction has been muted to the 90-day ban on travel to the US by citizens of Iraq, Syria, Iran, Sudan, Libya, Somalia and Yemen. The order also suspends refugee admissions for 120 days and indefinitely bars the processing of refugees from Syria.

OPEC members Saudi Arabia and the UAE, the Arab world’s largest economies, have bought billions of dollars’ worth of weapons from the US, and thousands of US troops remain stationed across the region.

Several Arab allies of the US have carried out air strikes against the Islamic State group and, more vitally, allow access to air bases and seaports supporting the bombing, reconnaissance and refuelling runs over Iraq and Syria.

Iraq, which is on the front lines in the fight against Islamic State group, is just over a third of the way through acquiring three dozen American-made F-16 fighters. It’s unclear how the ban will affect the Iraqi pilots, who are trained in the US.

The Iraqi Air Force Commander, Lt Gen Anwar Hama Amin, initially said the military has yet to receive a “clear response” on whether the ban applies to members of the Iraqi security forces.

“I’m worried and surprised,” he said. “We are fighting terrorism and this order will affect the fighting. … I hope this order will be reconsidered.”

Amin later said American officials told him the pilots wouldn’t be affected by the US ban. The US Central Command did not respond to a request for comment.

US senators John McCain and Lindsey Graham, both Republicans and retired military officers, have warned Trump’s immigration order could become “a self-inflicted wound in the fight against terrorism.”