US President Donald Trump has said Ukraine "may be Russian someday," or it "may not be Russian someday." The remark comes as he explores a deal to gain Ukrainian natural resources in exchange for continued American military support.

In an interview with Fox News aired on Monday, Trump noted that Ukraine has "tremendously valuable land in terms of rare earth, in terms of oil and gas, in terms of other things."

Referring to US military support to Ukraine, Trump said: "I want to have our money secured, because we're spending hundreds of billions of dollars."

He added Ukrainians "may make a deal, they may not make a deal."

The remarks are causing controversy, as it could be interpreted as accepting the cession of Ukrainian territory to Russia.

Meanwhile, Trump's special envoy for Ukraine and Russia, Keith Kellogg, spoke with Reuters news agency on Monday. He said the shipments of US weapons, which were approved by former US President Joe Biden, are still flowing into Ukraine.

Kellogg is due to visit Ukraine sometime soon, and US Vice President JD Vance is scheduled to hold talks with Ukrainian President Volodymyr Zelenskyy on Friday.