Speaking to reporters, Obama thanked Australia for its efforts as part of the 60-nation coalition against IS in Iraq and Syria, saying it "is the second largest contributor of troops on the ground after the United States."
Obama said he and Turnbull would discuss how "we can strengthen our cooperation, both in Syria and Iraq, the state of affairs in Afghanistan, but also countering violent extremism globally."
Turnbull -- who recently visited coalition troops in Iraq and Afghanistan -- praised the openness of U.S. intelligence agencies, saying it yielded "very productive discussions." He also commended the efforts of Australian and U.S. troops who worked together in supporting the Iraqi security forces that recently recaptured the IS-held city of Ramadi.
"It was a great combination of our servicemen and women working with the Iraqis to achieve that," Turnbull said.
Also discussed were the benefits of the TPP, a trade agreement reached last year by 12 Pacific Rim countries, including Australia, the United States, Canada, Japan, Malaysia, Mexico, Peru, Vietnam, Brunei, Chile, New Zealand and Singapore.
"We are both part of the driving force that created this rules-based system that is now being prepared to ratify among the various nations," Obama said.
A recent World Bank report suggested the TPP would benefit the economies of the United States and Australia the least, boosting the Australian economy by 0.7 percent and the American economy by 0.4 percent by 2030.
Still, Obama said the trade agreement would be good for workers and businesses and it "reaffirms that in order for us to thrive in the 21st century, particularly economies that are respectful of rule of law and concerned about labor rights and environmental rights, it's important for us to be making the rules in this region, and that's exactly what TPP does."
For his part, Turnbull said the TPP is "much more than a trade deal."
"I think when people try to analyze it in terms of what it adds to this amount of GDP or that, that's important," Turnbull said. "But the critical thing is the way it promotes the continued integration of those economies, because that is as important an element in our security in the maintenance of the values which both our countries share as all of our other efforts -- whether they are in defense or whether they are in traditional diplomacy."
Turnbull also complimented the United States on its leadership regarding the Iran nuclear deal and agreed with Obama that Australian and U.S. values were one and the same.
"I thank you very much for your hospitality, for your generosity, and the way in which -- typical of the relations between Australians and Americans -- we have been able to speak candidly at all levels of your government, in a common cause," Turnbull said, "because the values we share are the values not just for these times, but for all time."