China's president Xi Jinping had visited a rare earth processing plant last week, which was seen as leverage for trade talks given the country's dominance in supply.

Chinese media reports yesterday then warned the US not to "underestimate China's ability to strike back", Reuters reported.

"The outcome of this has to be an increased focus outside China on rare earths production because while China has a near monopoly on rare earths production, there's going to be a scarcity of supply for world markets as it uses all its production internally," Alkane Resources (ASX: ALK) marketing general manager Alister MacDonald said today.

The gold miner also has the construction-ready zirconium, hafnium, niobium, yttrium rare earth project in New South Wales.

Happily-named junior Rare Element Resources (OTCQB: REEMF) demonstrated the investor interest.

Its share price rose about 150% yesterday, to close at US59.9c, having touched a 52-week high intraday of 60.01c.

The company had said in February it was planning to proceed with a pilot plant "during the first nine months of 2019" to further test its proprietary rare earth separation technology.

In Toronto, Critical Elements Corp (TSXV: CRE) rose almost 28%. It recently awarded the early contractor involvement contract for its Rose lithium-tantalum project in Quebec.

Alkane's shares rose more than 12% yesterday but were down 3% in afternoon trade today, while integrated rare earth producer Lynas Corp (ASX: LYC) was a further 1.2% higher after yesterday's 15.5% gain.

Elsewhere, key global market indices closed lower yesterday and the S&P/ASX200 was down at the time of writing.