BHP and Rio Tinto were on the invitation list for a critical minerals roundtable at the White House on Friday, Washington time, one of a group of miners the Trump administration brought in to discuss cutting United States reliance on Chinese-controlled supply.

Both companies have a direct interest in the meeting's subject. Rio Tinto operates the Resolution Copper project in Arizona on a 55 per cent interest, with BHP holding the remaining 45 per cent. The ore body sits more than 1600 metres underground about 100 kilometres east of Phoenix, and the partners have said the mine could supply more than a quarter of United States copper demand.

The meeting was convened around President Donald Trump, with Interior Secretary Doug Burgum, National Energy Dominance Council executive director Jarrod Agen and White House adviser David Copley involved. Invitations went to Freeport-McMoRan and MP Materials, the largest American copper and rare earths producers, along with USA Rare Earth, Energy Fuels, United States Antimony and The Metals Company. All 14 accredited United States mining schools were invited as well.

Resolution Copper cleared its longest-running obstacle earlier this year. The congressionally mandated land exchange with the federal government completed after a 13 March decision by the United States Court of Appeals for the Ninth Circuit went in favour of Resolution Copper and the government. Rio Tinto has since set out roughly US$500 million of enabling works over two years, its own share US$275 million, covering surface drilling, infrastructure upgrades, funding for Native American tribes and local communities, and early underground development. About 100 jobs come with it.

Those jobs are in Arizona. So is the ore, the processing that follows it, and the supply security the administration is buying. What comes back to Australian holders is a share of earnings. The capital is raised against ASX-listed stock; the industrial base being built with it is American.

The market took the invitation as a mild negative. BHP shares fell 0.4 per cent and Rio Tinto 0.7 per cent on Thursday after the meeting was first reported. The S&P/ASX 200 closed that session at 9,271.60, up 43.8 points and a record, then gave back 8.00 points on Friday to finish at 9,263.60.

Neither company had announced an outcome from the roundtable at the time of publication, and no binding commitment was flagged in advance. The administration's stated aim is to replenish defence stockpiles and reduce dependence on Chinese processing, which is a policy objective rather than an offtake contract.

The number that matters for Australian holders is the production date. Rio Tinto has said it is working towards first copper from Resolution by the end of the decade. Everything announced in Washington on Friday sits upstream of that.