Morning mail: Trump's ban on transgender troops Thursday: US president faces backlash after reversing Barack Obama's policy. Plus Australia targets red imported fire ants Donald Trump speaks to US military personnel at naval air station Sigonella following the G7 Summit, in Sicily, Italy. Photograph: Darrin Zammit Lupi/Reuters Eleanor Ainge Roy @EleanorAingeRoy Good morning, this is Eleanor Ainge Roy bringing you the main stories and must-reads on Thursday 27 July. Top stories Donald Trump has said he will not allow transgender people to serve in the US military, reversing a policy put in place by Barack Obama a year ago. In a series of tweets the US president explained his decision: "Our military must be focused on decisive and overwhelming … victory and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail." Backlash to Trump's decision was immediate and transcended party lines. Arizona senator John McCain, who chairs the Senate armed services committee, said: "Any American who meets current medical and readiness standards should be allowed to continue serving. There is no reason to force service members who are able to fight, train and deploy to leave the military – regardless of their gender identity." There are roughly 1.4 million active-duty US service members. A 2016 study by the Rand Corporation estimated there are up to 6,630 trans people on active duty and up to 4,160 in the select reserve. Australia is launching a $411m biosecurity operation to eradicate deadly red fire ants. The blitz aims to destory the venomous South American species that threatens agriculture, wildlife, tourism and Australia's outdoor lifestyle. Without a major push, which is being spearheaded by an unlikely alliance of environmentalists and farmers, experts say outbreaks will spread and lead to an uncontrolled population that would have a bigger impact than rabbits, cane toads, foxes, camels and feral cats combined. First detected in Australia in 2001, but probably brought in years earlier, the ants are thought to have caused dozens of deaths in the United States, where they have become established and cost the economy $7bn a year. The ants are extremely aggressive, attacking en masse and inflicting an itching and burning sting that can last an hour. In rare cases allergic reactions can kill. Tony Abbott has backtracked on a previous statement that Liberal MPs would not be bound on same-sex marriage beyond the last parliament and he says the government must stick with the plebiscite policy until the next election. Abbott used a radio interview on Wednesday to insist the Liberal party was "honour bound, by pledge of the Australian people, not to try and change this matter in the parliament". The comments will force the Liberal party into an internal debate about its stance on marriage equality once parliament resumes after the winter break because the Western Australian senator Dean Smith is bringing forward a private member's bill calling for a free vote on the issue. Matt Canavan's account of unwittingly becoming a dual citizen, a revelation that threatens his standing as an MP, could only have taken place in a highly unusual departure from Italian immigration rules, experts have said. Canavan, who was until Tuesday the minister for resources and northern Australia, quit cabinet while remaining a senator, saying his mother had arranged his Italian citizenship without his knowledge. Sara Bucalossi, a visa procurement associate at Marschetti, one of Italy's largest immigration law firms, said there was no way parents could apply for citizenship on behalf of their adult children. Every application – in Italy or abroad – must be carried out in person. Guardian Australia has won three of the Walkley midyear awards. Paul Farrell won young journalist of the year and the public service journalism award for Guardian Australia's Nauru Files series, which revealed the scale of abuse of children and rates of self-harm in Australia's offshore detention regime through the publication of more than 2,000 leaked reports. Kate Hennessy won the Walkley-Pascall award for arts criticism for her review of Leah Purcell's play The Drover's Wife. Sport Novak Djokovic. Photograph: Joe Toth/PA Tennis superstar Novak Djokovic will bow out of the 2017 season after a turbulent few months battling an elbow injury. Djokovic announced the "prolonged break" on his official website after injury forced the world No 4 to retire from the Wimbledon quarter-final this month. Andre Agassi will stay on as his coach until next year. "I will take this time to heal and ... get back on the court as soon as possible," Djokovic said. The Wallabies are embarking on gruelling mental and physical training sessions in preparation for meeting the All Blacks in the opening match of the Bledisloe Cup on 19 August. Coach Michael Cheika is focused on improving his squad's fitness as well as their mental fortitude, and even had them run up hills with their mouths taped shut to force them to breath through their noses. Tough. Thinking time More than 70% of Australians play video games. Photograph: Matjaz Slanic/Getty Images To win one of the estimated 700 full-time jobs in the billion-dollar Australian gaming industry, you have to be better than good; you have to be exceptional. We've profiled some of the people who use their imaginations and ingenuity to challenge and entertain the more than 70% of Australians who play video games. "I feel like I'm living through them somehow," says Leonie Yue, an illustrator, studio artist and character designer. "I like to be part of something positive, hopeful, weird, silly, beautiful ... My dream is to be one of the best character designers out there. One day!" The Australian Bureau of Statistics is releasing new data that aims to bring a number of labour force figures into sync. The "Labour Account", released for the first time this week, shows an increase in the number of people working two jobs. Greg Jericho says "in time it will give us more information on the changing nature of our labour force". Australian Ninja Warrior ended on Tuesday night without a winner – but with a record-breaking 3.087 million viewers. Across the entire global franchise, only seven people have completed the course – so without the pay-off of a victory, why did so many watch it? What's he done now? As well as his transgender bombshell, Donald Trump has called illegal immigrants "animals" and announced a crackdown on "sanctuary cities". Speaking in Ohio, he said: "They'll take a young, beautiful girl, 16, 15 and others. And they slice them and dice them with a knife. Because they want them to go through excrutiating pain before they die. And these are the animals that we've been protecting for so long. Well they are not being protected any longer folks. And that is why my administration is launching a crackdown on sanctuary cities." Media roundup The Australian has an exclusive revealing the identity of the young woman who was found dead in the hotel room rented for a buck's party in Melbourne in June. Natasha Rowley, 20, had officially become a soldier in the Australian army just four months before her as yet unexplained death. The NT News has a striking front-page dedicated to the life of Dr G Yunupingu, and a number of other newspaper also devote their front pages to the renowned singer. The Herald Sun has a sweeping front page on Cardinal George Pell's return to Australia: "Rome to Home" the headline says. The Age, the West Australian and the Canberra Times follow suit. The ABC reveals that an inquiry into the activities of Australian special forces in Afghanistan is investigating allegations an SAS member gunned down an Afghan businessman and then planted a pistol on the body to make it look like self-defence. Coming up Boris Johnson, the UK foreign secretary, will deliver the annual Lowy lecture and take part in a Q&A with the Lowy Institute's executive director, Michael Fullilove. Johnson will also hold a joint press conference with Julie Bishop, the foreign affairs minister, and defence ministers from both countries as part of the AUKMIN talks. Support the Guardian It might take a minute to catch up on the news, but good journalism takes time and money. If you already support Guardian Australia, your generosity is invaluable. If not, and you value what we do, please become a Supporter today. Thanks. Guardian News & Media Limited - a member of Guardian Media Group PLC. Registered Office: Kings Place, 90 York Way, London, N1 9GU. Registered in England No. 908396