Ruffling U.S. ties with one of its closest allies, President Trump is sharply criticizing an Obama-era agreement with Australia — a deal that also reportedly prompted the American leader to tell Australia's prime minister that his was the "worst" phone call Trump received after his inauguration.Late Wednesday night, the president vented his anger on Twitter, saying: "Do you believe it? The Obama Administration agreed to take thousands of illegal immigrants from Australia. Why? I will study this dumb deal!"As the Australian Broadcasting Network notes, Trump's tweet "incorrectly labels refugees 'illegal immigrants' and cites 'thousands' of people instead of 1,250."The deal concerns refugees, many of them children, who've been housed in offshore detention centers on Nauru and other islands. The arrangement has been controversial in Australia, particularly after incidents of abuse emerged.Speaking to a radio station in Sydney, Australian Prime Minister Malcolm Turnbull says he's aware Trump doesn't like the agreement, but, he added, the question is will he commit to honor the deal. He has given that commitment."Turnbull also said he's disappointed that details about his communication with Trump were leaked.After news of the apparent rift emerged, Sen. John McCain said he called the Australian ambassador "to express my unwavering support for alliance" with the country that he described as one of America's oldest friends and allies. THe two allies, McCain noted, have fought together from World War I to Vietnam and the conflicts in Iraq and Afghanistan.From Melbourne, Louisa Lim reports for our Newscast unit: