What Australia and the United States are now trying to work out is how to manage that military momentum in an increasingly tense part of the world. If the military is a hammer in the Trump era, at what point does every dispute start to look like a nail?
“It’s always important that there’s a balance between the military and the diplomatic — because of the scale of the military,” Mr. Keating said in an interview. “In both economic terms and in strategic terms, they squeeze diplomacy out.”
Darwin, a humid, crocodile-infested coastal city at the northern end of this vast country, captures the past, present and future of Australia’s alliance with the United States.
Japan attacked the city on Feb. 19, 1942, killing 235 people, and residents are quick to point out that the raids were led by the same commander responsible for the attack on Pearl Harbor 10 weeks earlier.
Within a few months, Darwin became a hub for counterstrikes from bombers flown by Americans. A pocket guide for arriving American troops set the tone: “You’re going to meet a people who like Americans and whom you will like.”
During the Cold War, the relationship expanded.
Kim Beazley, a former defense minister and ambassador to the United States, cited the rise during the 1960s of three joint installations to maintain contact with American submarines in the Indian Ocean and provide infrared detection of Soviet capabilities, increasing the warning time for a potential Soviet strike to 30 minutes from 15.
Those installations and the ones that followed — especially Pine Gap, a joint Australian-American spy base that helps provide battlefield intelligence and early warnings for missile launches around the world — “are never talked about, but they’re really the guts of the alliance,” Mr. Beazley said.
On the ground in countries like Iraq and Afghanistan, Australian troops are also peers in battle, said Lt. Col. Brian S. Middleton, commanding officer of the Third Battalion, Fourth Marines — the American unit that just moved into Darwin for six months of training with the Australians.
As part of the American pivot to Asia, the long-term plan, negotiated under the Obama administration, is to send up to 2,500 Marines to Darwin — the largest deployment of United States forces to Australia since World War II. “It’ll make us more effective in whatever conflict we end up serving in together,” said Kelly Magsamen, the Pentagon’s top Asia-Pacific policy official at the end of the Obama administration.
Other American officials said that in space, missile defense and cyberwarfare, the Australians are all in. Australia is working with the United States to relocate a special radar that helps better track satellites. The Australian military is also making a big push in innovation in undersea warfare and drones in the air and underwater.
And in many cases, that means purchases of American equipment. An Australian defense planning report last year laid out a $20 billion increase in the annual military budget by 2025, including money for fighter jets, surveillance technology, submarines, surface ships and other equipment.
Australians are embedded at every level of the American military. Australian Air Commodore Phillip Champion’s story is common: He first worked with the Americans as a young pilot in the early ’80s, flying surveillance aircraft, and later as a commander all over the world, including Afghanistan.
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