LONDON (AP) — King Charles III is preparing to visit Australia and Samoa in October, an itinerary that will span 12 time zones and test the monarch’s stamina as he recovers from cancer treatment.

The trip, announced on Sunday by Buckingham Palace, marks a watershed moment for the 75-year-old king, who has been slowly returning to public duties after taking a break following his cancer diagnosis in early February. The decision to undertake such a long journey will be seen as a sign of Charles’ recovery, even though the program in Australia will be “limited.”

The visit to Australia will be a critical moment for the king as he tries to shore up support for the monarchy at home and abroad. The trip will mark the first time since he ascended the throne that Charles will visit one of the 14 countries outside the United Kingdom where the British monarch remains head of state, a link that is a source of pride for some but an unwelcome reminder of Britain’s colonial dominance for others.

While he will undoubtedly be welcomed by fans waving the flag and singing “God Save the King,” Charles is also likely to hear anti-monarchy voices in a country where 45% of voters in a 1999 referendum supported creating an Australian republic. Prime Minister Anthony Albanese’s Labor Party supports ditching the monarchy, but the government says it isn’t a priority and there is no timeline for another referendum.

“It’s clear that there’s a real reevaluation going on there as to whether the Commonwealth, and certainly the realms, want to retain their connection to the British monarchy or not,” Ed Owens, a historian and author of “After Elizabeth: Can the Monarchy Save Itself?” told The Associated Press in an interview before the trip was announced. “So, you know, there are troubled waters ahead.”

Albanese said he and Governor-General Sam Mostyn, the monarch’s representative in Australia, would welcome Charles and Queen Camilla. Albanese noted Charles had already made 15 official visits to Australia, the most recent in 2018. The monarch had also spent several months in an Australian bordering school as a teen in 1966.

“The King has a deep regard for our great nation, and has always spoken warmly of the time he has spent here and the astounding beauty of our extraordinary continent,” Albanese said in a statement.

The palace provided few details of the tour. Charles and Camilla will visit the Australian Capital Territory and New South Wales as well as making a more formal state visit to Samoa, where the king will appear at the Commonwealth Heads of Government Meeting, the palace said.

The capital territory is home to Canberra, Australia’s national capital. Sydney, Australia’s largest city, is in New South Wales.

Charles holds the symbolic title of head of the Commonwealth, a voluntary association of 56 independent nations, most of which have historic ties to Britain. The annual heads of government meeting will be held Oct. 21-25.

However, the trip will not include a stop in New Zealand.

“The King’s doctors have advised that a further extension to Their Majesties’ trip should be avoided at this time, to prioritize His Majesty’s continued recovery,” the palace said in a statement.

Albanese said planning for the visit was still underway and more information would be made public in due course.

Isaac Jeffrey, national director and CEO of the Australian Republic Movement, the peak body advocating for an Australian republic with an Australian head of state, called for a meeting with Charles and questioned why Australia should pay for the royal visit.

“This visit is a great opportunity for all Australians to ask themselves whether the British Royals really represent a modern Aussie democracy,” Jeffrey said in a statement.

The trip comes at a time when the health problems of Charles and Kate, the Princess of Wales, have highlighted the challenges faced by a slimmed-down royal family as the king pledges to cut costs.

With fewer working royals available to carry out the endless round of ribbon cuttings, awards ceremonies and state events that make up the life of a modern royal, the remaining family members have been forced to take on more events.

Charles’ cancer diagnosis occurred at the same time that the Princess of Wales — one of the most popular royals — underwent abdominal surgery and later announced she, too, had cancer. Prince William took time off to support his wife and their young family.

That left Camilla, the king’s sister, Princess Anne, and his youngest brother, Prince Edward, to shoulder the load. Princess Anne was briefly hospitalized last month after an accident thought to involve a horse left her with a concussion.

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Associated Press writer Rod McGuirk in Melbourne, Australia, contributed to this report.