US Secretary of State Condoleezza Rice and her counterparts from Australia and Japan have expressed grave concern over Iran's disputed nuclear programme.
Iran and North Korea topped the agenda of the security meeting
In a joint statement following trilateral security talks, they called on Iran to suspend uranium enrichment activities and resume negotiations.
The US has accused Iran of seeking to build nuclear weapons, which it denies.
Speaking earlier during her visit to Australia, Ms Rice called for better relations between Japan and China.
Ms Rice, Australian Foreign Minister Alexander Downer and Japanese Foreign Minister Taro Aso said they discussed the need for "concerted action" by the UN Security Council to convince Iran to "promptly suspend" uranium enrichment activities.
They urged Iran to return to talks with the UN's nuclear watchdog, the International Atomic Energy Authority (IAEA), and comply with its demands.
The UN Security Council is currently discussing what action to take against Iran, after months of growing tension over the country's nuclear programme.
The three ministers also called on North Korea to "immediately and unconditionally" return to six-party nuclear talks.
The six-party talks, involving North and South Korea, China, Japan, Russia and the US, appeared to reach a breakthrough in September when North Korea agreed to give up its nuclear programme in exchange for aid and security guarantees.
However no progress has since been made on implementing the agreement.
Earlier, Ms Rice and her counterparts held talks on how the three countries could deal with issues such as China and tackle its growing military strength.
Ms Rice had voiced concerns that Beijing would become a "negative force" unless it was more open about its military build-up.
"Though there are difficulties... China and Japan also share a lot of interests," Ms Rice said in Sydney after meeting Australian Prime Minister John Howard.
"There is a lot to work with in the Japan-China relationship and we've encouraged that relationship to get better and better," she said.
Australia has argued the meeting should not be seen as a bid to "contain" China but at ensuring a working relationship.
"China, as it's a growing power, as it's an emerging power in the region, is a country that needs to understand that brings a level of responsibilities," Foreign Minister Downer said.
"It has a responsibility to make sure that it works comfortably and constructively with other countries in the region, that it makes a positive contribution to regional as well as to global issues."