Cove Kaz Capital, a U.S. citical minerals company linked to two of U.S. President Donald Trump's sons through its planned merger with Skyline Builders, asked the U.S. Defense Department's Office of Strategic Capital for an additional $400 million to develop the Northern Katpar and Upper Kairakty tungsten projects in Kazakhstan, the Financial Times reported on May 12.

The request would add to earlier nonbinding letters of interest for up to $1.6 billion from the U.S. Export-Import Bank and the U.S. International Development Finance Corp. Cove Kaz controls 70% of the projects, while Kazakhstan's state mining company Tau-Ken Samruk holds the remaining stake. Cove has described the assets as the largest tungsten project outside China, with plans to break ground in 2028 and begin mine commissioning in 2029.