SYDNEY, Australia -- The U.S. appeared set to grant Australia an exemption from its new tariffs on steel and aluminum imports following discussions between President Donald Trump and Prime Minister Malcolm Turnbull.

Trump this week exempted Canada and Mexico from the duties -- 25 per cent on steel and 10 per cent on aluminum -- and said U.S. allies would have 15 days to negotiate possible exemptions.

That triggered a diplomatic offensive from Australia, including a letter to Trump signed by business leaders and former Australian golfing great Greg Norman, a Trump supporter and friend.

After a telephone call with Turnbull on Friday, "Spoke to PM ΓåòTurnbullMalcolm of Australia. He is committed to having a very fair and reciprocal military and trade relationship."

"Working very quickly on a security agreement so we don't have to impose steel or aluminum tariffs on our ally, the great nation of Australia!"

Turnbull went a step further, telling reporters in South Australia on Saturday that he was "very pleased the President was able to confirm that he would not have to impose tariffs on Australian steel and aluminum."

There appeared some doubt between the two countries over Trump's choice of words. While the Trump highlighted the nations' military and trade relationships, Turnbull moved to clarify Trump's comment about a new "security agreement," saying the president was referring to the legal paperwork that would lock the exemption into place.

Turnbull added Australia had "the closest possible military and security alliance with the United States and it gets closer all of the time."

Australia buys around 60 per cent of its military assets from the U.S., allows U.S. marines to rotate through Darwin every year, and swaps intelligence as part of the "Five Eyes" alliance also including Britain, New Zealand and Canada.

"Our trade relationship, as the president acknowledges, is a fair and reciprocal one," Turnbull said. "It's absolutely, it's a level playing field and, in fact, the U.S. has a large trade surplus with Australia."