SYDNEY (Reuters) - Senior US officials said on Monday (June 5) the United States, under President Donald Trump, was committed to the region, reassuring nervous global partners even as it received criticism for pulling out of major a climate pact.

Global leaders have said there was growing mistrust of the Trump administration, especially because of his withdrawal from the Trans-Pacific Partnership on trade and from the Paris climate accord.

Mr Trump's "America First" rhetoric and expectations that he would concentrate on a domestic agenda has stoked fears of a retreat from a traditional U.S. security role that has underpinned the region for decades.

But US Secretary of State Rex Tillerson said the Trump administration should be judged for its actions and not words.

"I hope the fact that we are here demonstrates that is certainly not this administration's view or intention to somehow put at arm's length the other important allies and partners in the world," Mr Tillerson told reporters in Sydney.

"That's why we're here ... That's why we engage with our counterparts," Tillerson said.

He is in Sydney for an annual conference along with US Defence Secretary James Mattis, Chairman of the Joint Chiefs of Staff Joseph Dunford and the head of Pacific Command Admiral Harry Harris.

Diplomatic ties were stained between the United States and Australia this year following a row over asylum seekers when Mr Trump described a refugee swap arrangement as a "dumb deal" on Twitter.

Despite the public dispute, Australian Foreign Minister Julie Bishop said the nature of the bilateral relationship extends beyond the superficial.

"We deal with the president, with his cabinet, and with the US administration on what they do, what they achieve, what their strategies are, and how we can work together," Ms Bishop said.

While Australia's government said it has not lost faith in the United States as a global leader, the decision to leave the Paris Climate agreement has drawn a wave of global criticism.

Speaking for the first time on the decision, Mr Tillerson appeared to distance himself from it, saying that it was Mr Trump's"judgment" that the climate pact did not serve the American people.

ENGAGING WITH ASIA-PACIFIC

With growing fears that the United States could not be relied on to maintain a buffer against China's assertiveness, several Asian nations have bolstered informal alliances among themselves.

Although reiterating US commitment to Asia, Mr Tillerson said China should do more on the issue of North Korea, which has stepped up its nuclear and missile programmes in defiance of US pressure and UN resolutions.

North Korea has become a security priority for Washington since it vowed to accelerate its nuclear and missile programmers and to develop a nuclear-tipped missile capable of hitting the US mainland.

Mr Tillerson also said the United States could not allow China to use its economic power to "buy its way out of other problems, whether it's militarising islands in the South China Sea or failing to put appropriate pressure on North Korea".

Reacting to his comments, Chinese Foreign Ministry spokeswoman Hua Chunying said: "We hope the relevant side can fully respect and support the efforts of countries in the region to maintain peace and stability in the South China Sea, and play a constructive role rather than the opposite".

Some US officials have also expressed concern about the growth of Islamic State in Iraq and Syria (ISIS) and the return of foreign fighters in the region and said it is one reason the United States will continue to remain engaged.

Authorities in the region have urged greater cooperation to counter the fallout from a raging battle with ISIS-linked militants in the southern Philippines, the biggest warning yet that the ultra-radical group is building a base in South-east Asia.

The region is home to 600 million people and includes Indonesia, which has the world's highest number of Muslims. Authorities in both Indonesia and Malaysia, also Muslim-majority, have said thousands of their citizens are sympathisers of ISIS and hundreds are believed to have travelled to Syria to join the militant group.