US Secretary of State Mike Pompeo has heard directly of the grief felt by families of those who died aboard Malaysian Airlines Flight 17, with a letter from Perth dad Anthony Maslin read to him at a media conference.

Mr Maslin and Rin Norris lost three children – Otis, Evie and Mo – when MH17 was shot down over Ukraine by a Russian missile four years ago.

The children’s grandfather, Nick Norris, also died. All 298 passengers on the flight, including 38 Australians, were killed.

A reporter read Mr Maslin’s letter to Mr Pompeo at a media conference on Wednesday morning (AEST) at the conclusion of the annual Australia-US Ministerial (AUSMIN) talks in California.

Afterward, Mr Pompeo said the US would continue to hold Russia accountable for the lives lost when the plane was shot down.

“We need the Russians to continue to be held accountable for that,” Mr Pompeo said. “We take this matter seriously.”

Mo, Evie and Otis Maslin, who died in the MH17 crash. Photo: AAP

The US delegation described the US-Australian alliance as “rock solid” at the conclusion of the two-day talks as they look to shore up the Trump administration’s regional policy.

“The US and Australia both know we can rely on each other,” Mr Pompeo said.

US Defence Secretary James Mattis added: “The US and Australia will walk the walk in the Indo-Pacific”.

A small, but vocal group of protesters accompanied by a large inflatable “Trump Chicken” stood outside Stanford’s Hoover Institution where the talks were held.

Mr Trump has used Twitter and public events to attack US allies, including Britain and Germany, and has sparked a potential trade war with tariffs on friendly nations.

Foreign Minister Julie Bishop and Defence Minister Marise Payne said the US-Australia alliance remained strong.

“We don’t always agree with the US and the US doesn’t always agree with us, but we are able to work through any differences in a very constructive and positive way and will continue to do that,” Ms Bishop said.

The talks confirmed the “full implementation” of force posture initiatives between US and Australian forces in Australia, including the commitment to raise the number of Marines in Darwin to the full complement of 2500 “as soon as practicable”.

The US and Australia also signed a memorandum of understanding to collaborate in researching and developing advanced cyber capabilities.

The nations were careful with their words on China’s militarisation and island building in the South China Sea and courting of Pacific nations.

“We have spent a lot of time over the course of the last two days talking about how to maintain a free and open Indo-Pacific,” Mr Pompeo said.

“That emanates from a lot of places – certainly China poses concerns there.”

Mr Mattis said it was up to Australia if it embarked on freedom of navigation exercises in the South China Sea.

“That’s a sovereign decision by a sovereign state,” he said.

Mr Pompeo said he was confident South Pacific nations would choose the US ahead of China, despite the Asian’s power’s move to make economic and strategic advances with small island nations.

“I think the South Pacific, like most places in the world, understands the enormity of having an American ally – a country that consistently over decades projects the democratic values,” he added.

“The human dignity that comes with having an American partner is different from having partners that aren’t quite that way.

“I think over time that will ultimately prevail, not only in the South Pacifc, but all across the world.”

-AAP