Trump signed his executive order for the ban on Friday, which sparked protests at airports in New York, Boston, Los Angeles, and other cities. Four federal judges in New York, Massachusetts, Virginia, and Washington state, subsequently issued stays on a ban that Cuban characterized, in a series of tweets over the weekend, as “not vetted or thought through.”

Cuban, like Trump himself, is a reality TV personality—having appeared on ABC’s Shark Tank for the last few years. And, like Trump, he is a Twitter (TWTR) aficionado. Cuban is a self-made billionaire who sold startup Broadcast.com to Yahoo (YHOO) in 1999 for $5.7 billion. And he has never been shy about sharing his opinions—whether the topic is NBA officiating or telecommunications policy, or politics.

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Some tech leaders were also unsettled by Trump’s orders, which suspended the country’s refugee program and temporarily banned visas for citizens of Iraq, Syria, Iran, Sudan, Libya, Somalia, and Yemen. Critics have pointed out the conspicuous absence of Saudi Arabia, and other predominantly Muslim countries that have been tied to the Sept. 11 attacks on the U.S. but that also have strong business ties with this country.

On Saturday, Google chief executive Sunder Pichai, for example, told Google (GOOG) employees traveling abroad who would be affected by the executive orders to return to the U.S. as soon as possible.

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https://twitter.com/mcuban/status/825563211915223041

https://twitter.com/mcuban/status/826044887409766400

Business Insider has more about the latest tweetstorm, which came a day after Cuban criticized Trump’s policy on Mexico, saying the president’s plan to impose a 20% tariff on Mexican imports would lead to a trade war.

For more on reaction to Trump’s travel ban, watch:

Cuban endorsed Democrat Hillary Clinton in her bid for the White House last July but had previously toyed with the idea of backing Trump, as noted in this Fortune timeline.