In Donald Trump's America not everybody is welcome.

Even the prospect of him landing in the White House was enough to make large numbers of prospective US visitors change their plans.

"What we saw before the presidential election was a 4 per cent drop of people into the US coming from the UK and Japan, 5 per cent drop from people coming from Italy, 7 per cent from France and 10 per cent from Germany, and a commensurate increase here in Australia of visitors from those countries," Tourism and Transport Forum CEO Margy Osmond said.

President Trump's anti-Mexican rhetoric, the ban on many Muslims and now his ban on laptops in some US-bound aeroplanes will deliver an estimated $7 billion hit to the US tourism industry this year alone.

But it is the US's $370 billion-a-year conferencing and business events industry that's really in the firing line, according to the executive chairman of the Centre for Asia Pacific Aviation, Peter Harbison.

"I think any large international conference organiser that attracts people from all over the world would have to be reviewing whether they do it in the US at the moment," he said.

Most industries and professions have at least one conference a year, often drawing people from all over the world.

Now, thanks to Mr Trump, organisers of conferences in the US cannot guarantee who can get there.

"If they turn up at the gate and find 30 per cent of their delegates have been turned around then that could be a massive financial blow for them and also the prestige of having guest speakers turned away at the gates, it really hits an association," said Matthew Hingerty, the chairman of the Business Events Council of Australia.

Conferences are big business

As in the US, business events here are big business, contributing $30 billion to the economy and employing 200,000 people.

The problems in the United States have come at an opportune time for Australia after a 3 per cent fall in conference attendance last year.

However, as always, distance is a factor and competition from countries like Singapore is fierce, which is why the business events industry is asking the Federal Government for $10 million to help lure conferences that otherwise would have gone to the US.

"If we can just help them a little bit by helping to defray some of their costs I am sure we can turn this disadvantage to some of our competitors into an advantage for us," Mr Hingerty said.

Questions over motive of plane laptop ban

Mr Trump's ban on laptops on some flights into the United States caught most by surprise and has raised questions as to its real motive.

The President says it is necessary to fight terrorism. Others, like Australian National University terrorism expert Clarke Jones, have a different view.

"It certainly doesn't seem to, from my reading, do anything towards counter-terrorism," he said.

It certainly to me seems like more of a political move or something to do with his business interests even."

United States airlines are not included in the laptop ban.

However, the rapidly expanding Gulf carriers — Emirates, Etihad and Qatar — are, and they will shoulder most of the burden in what can be seen as an attack on their lucrative business class market.

Carriers in the US have been furiously lobbying the Whitehouse to put the brakes on the Gulf upstarts.

"It's mind boggling if it is that cynical. But once you eliminate all the other possibilities you just can't come to any other conclusion frankly," laments the Centre for Asia Pacific Aviation's, Peter Harbison.

ANU's Dr Jones also makes the point that there have been no terrorism-related incidents involving laptops.

"We don't ban mobile telephones on planes but mobile telephones have been used [in terror attacks] — not only with airlines, certainly with attacks occurring overseas, and using phones to detonate devices," he said.

It all adds up to the US being a much less friendly place for visitors wanting to attend a conference.

"There are long lead times in getting this business. Sometimes they are for a year, two years, three years out," Mr Hingerty said.

The challenge for Australia is to get some of that business and keep it.