By David Brunnstrom and Lesley Wroughton

WASHINGTON (Reuters) – U.S. Secretary of State Rex Tillerson has underscored Washington’s intent to strengthen ties with Australia, Japan and South Korea, the State Department said on Tuesday, a move aimed at reassuring allies unnerved by the campaign rhetoric of new President Donald Trump.

In separate calls with counterparts from the three long-time allies, they agreed to work closely to tackle threats from North Korea’s nuclear ambitions and increased tensions in the East and South China seas, State Department spokesman Mark Toner said,

“Secretary Tillerson reiterated the Administration’s intent to strengthen our military alliances, our economic partnerships, and our diplomatic cooperation,” he said in a statement.

Tillerson expressed interest in early meetings with his counterparts “and expressed his deep respect for their nations’ contributions to regional security, global prosperity, democratic institutions, and the rule of law,” it said.

The calls come at a time of raised concerns in the Asia-Pacific about Trump’s attitude to the region.

During his election campaign, Trump appeared to question U.S. alliances with Tokyo and Seoul and complained that they were not sharing enough of the cost of the U.S. security umbrella. Trump has also criticized Japan’s trade policies as damaging to U.S. jobs.

More recently ties with Australia were strained after details of an acrimonious phone call between Trump and Australian Prime Minister Malcolm Turnbull emerged and the former described a deal between the two nations on refugee resettlement as “dumb.”

Japanese Prime Minister Shinzo Abe is due to visit Washington for a two-day summit with Trump from Friday that is expected to focus on security ties in the face of a rising China and trade.

Earlier on Tuesday, Japan’s Kyodo news agency quoted Japanese Foreign Minister Fumio Kishida as saying that Tillerson had confirmed that a long-standing commitment by Washington to defend Japanese territory applies to the Senkakus, a group of small islands that China claims and calls the Diaoyus.

The State Department declined to comment on the Kyodo report but U.S. Defense Secretary Jim Mattis reaffirmed America’s commitment to its mutual defense treaty with Japan on Friday when he met Abe in Tokyo and in a call with Abe in late January. Trump said the U.S. security commitment was “ironclad.

Turnbull’s leadership was questioned after he was berated by Trump and an opinion poll published on Monday showed support for his coalition had slipped to its lowest level since he took power 17 months ago and that his Liberal-National coalition would easily fall if an election were held now.

(Reporting by Lesley Wroughton and David Brunnstrom; editing by Diane Craft, Bernard Orr)