Australian police have charged five men held earlier this week on suspicion of planning to travel in a small motor boat to Indonesia and the Philippines en route to join Islamic State in Syria.
The men, aged between 21 and 31, were charged with preparing to enter a foreign country "for the purpose of engaging in hostile activities," an offense that carries a maximum penalty of life imprisonment.
The five were arrested on Tuesday after towing the seven-meter motor boat almost 3,000 km (1,865 miles) from Melbourne to Cairns in northern Queensland state, police said.
They have been in custody since, and are not scheduled to face court until Monday.
"There's no current or impending threat of a terrorist act to the Australian community arising from this investigation," a police statement said.
Australia, a staunch U.S. ally, has been on heightened alert for attacks by home-grown radicals since 2014 and authorities say they have thwarted a number of potential attacks, while there have been several "lone wolf" assaults, including a cafe siege in Sydney that left two hostages and the gunman dead.
Approximately 100 people have left Australia for Syria to fight alongside organizations such as Islamic State, Australia's Immigration Minister said last month.
Police said earlier this week that it was unclear where the men had planned to put the boat in the water. Indonesia and Australia share a maritime border, but it spans several hundred kilometers of open sea at its narrowest point.
The Australian Broadcasting Corporation said Melbourne-born radical preacher Musa Cerantonio, a vocal supporter of Islamic State who was deported from the Philippines to Australia in 2014, was among those charged.
Cerantonio, who converted to Islam from Catholicism at 17, was believed to be planning to join the militant group when he was deported for having "invalid travel documentation." He was placed under surveillance but not arrested upon his return.
In the US, several attempts to recruit Americans to join the Islamic State in Syria have been foiled.
In March, Jaelyn Young, a former Mississippi State University student and her fiance, Muhammad Dakhlalla, pleaded guilty to attempting to aid a terrorist group, The Christian Science Monitor reported.
Mr. Dakhalla, 23, and Young, 20, both United States citizens, were apprehended last August while attempting to board a flight to Turkey en route to Syria, and IS. The couple was arrested at a Mississippi airport following a months-long investigation by federal agents.
Young's story follows a now-familiar pattern of young Westerners sympathetic to prejudice and persecution experienced by Muslims around the world turning to the brutal militant group. The Islamic State capitalizes on these sympathies, telling young people that they will be able to help marginalized Muslims by joining the militant group.
Young says she converted to Islam last March, and became invested in the treatment of Muslims in Western countries such as the US and Britain. She also began wearing a burqa and following the actions of IS online, calling the group "liberators."
"After her conversion, Young distanced herselffrom family and friends and felt spending time with non-Muslims would be a bad influence," a prosecution statement read, according to The Associated Press.
A sudden interest in Islam combined with social disconnection can be a red flag for families, but one that parents may be unsure how to address because they worry that involving authorities could land their children in jail, Christianne Boudreau, a Canadian mother who has started a program designed to support parents in family-based interventions, told the Monitor's Warren Richey last fall.
(Reporting by Tom Westbrook; Editing by Helen Popper)