Top U.S. cabinet ministers have arrived in Australia for critical talks on terrorism and North Korea in the wake of two attacks in Britain.

Secretary of State Rex Tillerson and Defense Secretary James Mattis landed in Sydney on Monday night for meetings with Australian counterparts on Monday.

The pair will discuss the important security topics with Foreign Minister Julie Bishop and Defence Minister Marise Payne in the annual AUSMIN dialogue.

U.S. Secretary of State Rex Tillerson (pictured) has arrived in Australia for critical talks on terrorism and North Korea in the wake of two attacks in Britain

He and Defense Secretary James 'Mad Dog' Mattis (pictured) landed in Sydney on Monday night for meetings with Australian counterparts on Monday

'Mad Dog' Mattis was greeted at the airport by Ms Payne as they shook hands at the foot of his plane's steps.

North Korea's missile tests, the recent spate of terrorist attacks and China's military build-up in the South China Sea are likely to dominate to long-awaited talks.

The talks are usually held annually, but it's been nearly two years since the last AUSMIN gathering because elections in the U.S. and Australia in 2016 made it difficult to schedule the high-level talks.

The pair will discuss the important security topics with Foreign Minister Julie Bishop (L) and Defence Minister Marise Payne (R) in the annual AUSMIN dialogue

North Korea's missile tests, the recent spate of terrorist attacks and China's military build-up in the South China Sea are likely to dominate to long-awaited talks

Ms Bishop said this round of talks would be one of the most important in many years.

'The strategic environment is changing rapidly and it's so very important for us to have an insight into the thinking of the new US administration,' she told Sky News.

It also gave an opportunity for Australia to put forward its perspectives and hopefully influence U.S. thinking as the Trump administration reviewed its foreign policy settings, she said.

Observers say terrorism is likely to be uppermost in the participants' minds given the recent deadly bombings in Manchester, Jakarta, Baghdad and Kabul.

Secretary Tillerson exits his plan at Sydney Airport ahead of high level talks on Monday

The talks are usually held annually, but it's been nearly two years since the last AUSMIN gathering

Secretary Tillerson leaves the airport in a waiting high-end car

But the most pressing issue facing Australia and the U.S. is North Korea's ballistic missile tests.

'The risk is that terrorism has been front of mind for the last couple of weeks, we've had Australians as well as Americans killed,' U.S. Studies Centre research fellow Dougal Robinson said.

'So the risk is they give terrorism far more billing than North Korea, which is a particularly important regional issue in Australia's region.'

Mr Robinson said the U.S. and Australian officials would discuss contingency operations and potential diplomatic approaches in relation to North Korea, which has sparked alarm across the region by carrying out nine missile tests this year.

Elections in the U.S. and Australia in 2016 made it difficult to schedule the high-level talks last year

The most pressing issue facing Australia and the U.S. is North Korea's ballistic missile tests

The U.S. and Australia urged China to put diplomatic and economic pressure on North Korea to end its missile program amid fears Pyongyang's long-range missiles could one day hit both nations.

Pyongyang warned Australia in April that it could be the target of a nuclear weapons strike if it continued to 'blindly' follow the U.S.

Ms Bishop said there was no doubt Mr Trump changed the dynamics of the discussion, and warned China it was not in its interests to have a nuclear-weaponised North Korea.

'It creates huge instability for the region; that's not in China's interests, it's not in anybody else's interests,' she said.

'Mad Dog' Mattis leaves his plane at Sydney airport and waves to those greeting him

U.S. and Australian officials would discuss contingency operations and potential diplomatic approaches in relation to North Korea

The U.S. and Australia urged China to put diplomatic and economic pressure on North Korea to end its missile program

But while the U.S. and Australia hope China can persuade North Korea to dump its missile program, they remain concerned by Beijing's construction of artificial islands in the South China Sea.

The U.S. sparked fury from China when a U.S. Navy patrol came within 12 nautical miles of one of the man-made islands last month as it carried out freedom of navigation patrols in the key trade route.

During a visit to Sydney this week, veteran Republican Senator John McCain accused China of being a 'bully' and suggested Australia consider joining the U.S. and other Asia Pacific neighbours in future patrols.

Secretary Mattis was greeted at the airport by Ms Payne as they shook hands at the foot of his plane's steps

Secretary Mattis chats to Ms Payne after he got down the plane's steps onto the tarmac

The group appeared to hit it off as they spent several minutes talking and laughing together

Mr Robinson also expects Australian officials at the meeting to stress Canberra's desire for the U.S. to have a broader economic and diplomatic engagement with Asia.

'There's a sense that U.S. engagement in Asia under the Trump administration is very military heavy,' he said.

Following the collapse of the Trans-Pacific Partnership trade deal and with a proposed budget cut to the State Department of 30 per cent, there are questions both in Canberra and the region about the nature of U.S. engagement in Asia,' he said.