President Donald Trump said his administration will “take a look” at businessman Peter Thiel’s allegations that Google’s work with China is “seemingly treasonous.”

Trump in a tweet Tuesday called Thiel “a great and brilliant guy who knows this subject better than anyone!” He added that “the Trump Administration will take a look!”

Google shares fell one per cent in pre-market trading after the tweet.

Thiel, one of Trump’s top Silicon Valley supporters and donors, took aim at Google and the tech industry over the companies’ focus on global markets while brushing aside U.S. interests in a speech Sunday in Washington.

Thiel, a Facebook Inc. (FB.O) board member, singled out Google for agreeing to work closely with China, trying to get its search engine back into the country, while deciding to let lapse a U.S. Defense Department contract that gave the military access to its artificial intelligence tools.

A spokesman for Google said the company doesn’t work with the Chinese military but declined to comment further.

Thiel argued that the kind of AI developed by DeepMind, which like Google is a subsidiary of Alphabet Inc., should be thought of as a potential “military weapon.” He then suggested Google’s actions were “seemingly treasonous,” asking whether DeepMind or Google senior management had been “infiltrated” by foreign intelligence agencies.

--With assistance from Max Chafkin.