Why won't Australia accept refugees who come by boat?
It's been a political football since the days of John Howard. Although as few as 2% of refugee arrivals come by boat, the Mudrock press makes a song and dance about stopping them, and our neanderthal LNP govt simply stated that no boat arrivals will be coming directly to Australia. They set up a new "camp" on Manus island of Papua New Guinea, because the other offshore detention camp at Naura in the south Pacific, was full to capacity.
After a series of "events" at Manus, including assaults, rapes, children tortured, etc. PNG closed Manus camp, and gave the govt a deadline for removing the refugees. They also offered settlement (with cash) for people to be assimilated into PNG's population, but hardly anyone wanted that.
To save face, our PM searched for any alternative to bringing them to our shores, at any price. Apparently Obama, in his last week of gracious send-off gifts to the people, made a promise to take them off our hands.
Trump is now rethinking this. It's what our LNP would call a "non-core promise". A line they've used in the past when blatantly going back on their word.