It was a big day for US tech investors this week, as US Citizenship and Immigration Services (USCIS) issued a list of more than 200 companies, including Facebook and Twitter, that are using digital assets to bring in foreign investors to invest in the US.

“We’re not going to let foreign money buy the future of our economy,” US Senator Richard Blumenthal, the top Democrat on the Senate Banking Committee, said during a hearing in September.

“We’re going to do what we can to encourage the companies that we want to invest here to invest by creating a legal environment that will allow them to invest.”

Last week, USCIS said that it was not taking any new applications for visas from foreign investors in the United States, although it did not specify what type of investment they might be looking for.

The agency said that the move to encourage companies to use digital assets in their investment plans came after the Trump administration decided in August to close its US-based border wall with Mexico, which has cost US companies $2.5bn a year.US President Donald Trump has vowed to build a “big, beautiful wall” on the border between the US and Mexico to stem the flow of illegal immigration.

The wall, which he has called the “greatest investment ever”, will reportedly cost $10bn to $15bn.

On Wednesday, USCIRS said that some US companies were using digital currencies as a way to attract foreign investors.

“Digital assets are now one of the hottest areas of investments in the world,” it said in a statement.

“This includes cryptocurrencies such as bitcoin, ethereum and litecoin, and blockchain-based systems that hold value in real time and can be traded on an exchange like the bitcoin exchange Bitstamp or on a smart contract platform like Ethereum.”USCIRS’ decision was welcomed by the National Venture Capital Association (NVCA), which has called on the government to use the visa process to ease pressure on the US economy.

“The United States is a global leader in the digital economy, and the recent announcements from USCIS to allow foreign investors into the US should serve as a wake-up call to all our industry leaders, investors, and regulators,” NVCA CEO David Zaslav said.

“It is imperative that our industry continue to be able to access foreign capital to invest and innovate, and this new visa process should provide a great starting point.”

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