The US ambassador says Washington and Canberra need to work together to maintain peace and stability in the Pacific.
Caroline Kennedy said the two nations had worked together for decades to support a rules-based order, lifting millions of people out of poverty.
Ms Kennedy said ongoing peace in the Indo-Pacific required a mix of diplomacy and deterrence.
"That's what we're going to continue to do," she told the ABC.
'We'll work with our partners and allies to make this safe."
Australia and the US have agreed to work together on projects in the Northern Territory and build a facility capable of housing six B-52 bombers and other aircraft.
The bombers are capable of being armed with nuclear weapons.
The two nations are also working together to upgrade airfields, fuel storage facilities, accommodation and training areas.
"America doesn't have a stronger, closer ally. I see that every day as I go around," Ms Kennedy said.
Asked about the housing of nuclear-capable bombers, Prime Minister Anthony Albanese said: "We engage with our friends in the United States alliance from time to time".
"There are visits to Australia, including in Darwin that has US marines on a rotating basis stationed there."
US bombers have visited Australia since the early 1980s and conducted training missions since 2005.
