WASHINGTON (AP):  Seeking to deepen their defence cooperation, the United States and Japan will soon sign a new five-year agreement on sharing the cost of the American military presence in Japan, Secretary of State Antony Blinken has said.

Speaking at the outset of a virtual conference between the US and Japanese foreign and defence ministers on Thursday, Blinken said Tokyo and Washington also will sign a deal on collaborating more closely in research and development of defence-related technologies, including ways to counter threats from hypersonic weapons.

The agreement on a new formula for sharing the cost of the American military presence in Japan ends a Trump-era dispute that had been a significant irritant in US-Japan relations. Blinken said the new deal will enable greater investment in the readiness of both countries' forces and improve their ability to operate together.

Defence Secretary Lloyd Austin, who participated virtually from his home because he is recovering from a COVID-19 infection, said the US-Japan alliance is increasingly important.

We're meeting against a backdrop of increased tensions and challenges to the free, stable and secure Indo-Pacific region that we both seek challenges posed by North Korea's nuclear ambitions and by the coercive and aggressive behaviour of the People's Republic of China, Austin said.

We remain grateful for the support that Japan continues to provide US forces deployed there and for an extraordinary level of mutual cooperation across the full spectrum of military capabilities, he added.

Concerns about China's growing military might were manifested in the signing of a defence agreement earlier Thursday between Japan and Australia, the first such pact Japan has sealed with any country other than the United States.

Thursday's talks could be complicated by the surge in coronavirus cases. Japan asked the US before the talks began to lock down American military bases on its soil due to the spread of COVID-19.

That request was made to Blinken by Japanese Foreign Minister Yoshimasa Hayashi in a one-on-one phone call before they joined Austin and Japanese Defence Minister Nobuo Kishi for the virtual conference. None of the four officials mentioned it directly in their introductory statements.

Speaking prior to the four-way conference, Hayashi said Blinken had promised the US would take utmost efforts to ensure people's health, but it was not immediately clear if a base curfew would be imposed. US Forces in Japan would not comment on the request, but said a team was carefully monitoring cases and trends.

The US military has vowed to take more stringent measures, including requiring all personnel, even those vaccinated, to wear masks on base until a third negative coronavirus test.

American forces have been criticised after a spike in coronavirus cases in areas where they are based in large numbers, including Okinawa and Iwakuni, both in southern Japan. COVID-19 cases among US Forces in Japan now total 1,784, about a third of them on Okinawa, according to USFJ. Iwakuni has reported 529 cases.

Yet Japanese Prime Minister Fumio Kishida's government clearly sees a benefit to the American military presence and shortly before Christmas agreed to a new cost-sharing pact with the United States that is expected to be formally signed on Friday in Tokyo.

Former President Donald Trump had railed about the costs of deployments of US forces abroad and had demanded that host countries, including Japan, pay significantly more for their upkeep than many were prepared to offer, badly straining relations with allies in Asia and Europe.

President Joe Biden's administration has sought to smooth those disagreements and last April resolved an impasse with South Korea over the costs of keeping US troops there. The Dec 21 consensus with Japan on a new four-year Special Measures Agreement is another tangible result of that policy.

Under the terms of the hosting deal, which will run to 2026, Japan will spend approximately 1.82 billion annually to support the US military presence. The US has about 55,000 troops in Japan, including a naval contingent, which makes it the largest forward-deployed US force in the world, according to the GAO.

Apart from cementing those terms, the US and Japan are hoping to increase cooperation and coordination on combatting China's increasing assertiveness in the Indo-Pacific region as well as explore ways to bring North Korea back to the negotiating table over its nuclear weapons programme.

The US and Japan are increasingly worried about threats from North Korea, which on Wednesday fired a ballistic missile into the sea in its first weapons launch in about two months.

The test of what the North says was a hypersonic missile was widely seen as a signal that Pyongyang isn't interested in rejoining denuclearisation talks anytime soon and would rather focus on boosting its weapons arsenal.

Despite repeated entreaties from the Biden administration the North has declined to rejoin even preliminary discussions on the nuclear issue. State Department spokesman Ned Price called on the North to refrain from further tests, which he said were a violation of UN Security Council resolutions, and urged it to respond to offers to restart the talks.