Over the weekend, openly defiant CEOs, particularly among the tech sector, expressed their displeasure with Trump's Friday executive order temporarily banning refugees and limiting travel from seven Muslim countries, with both words and deeds, among which the following (summary courtesy of Axios):

VCs funding the ACLU: Several venture capitalists, as well as a few entrepreneurs, took turns soliciting donations to the American Civil Liberties Union through social media and personally matching those donations.

Several venture capitalists, as well as a few entrepreneurs, took turns soliciting donations to the American Civil Liberties Union through social media and personally matching those donations. Airbnb volunteers to help provide housing for impacted immigrants: The home-sharing company said that it will work with travelers and organizations to provide housing for those impacted by the executive order, whether through volunteer hosts or by funding housing.

The home-sharing company said that it will work with travelers and organizations to provide housing for those impacted by the executive order, whether through volunteer hosts or by funding housing. Lyft and Uber commit millions of dollars to legal aid: On Sunday, Lyft said it will donate $1 million to the ACLU over the next four years. Later in the day, Uber said it will create a $3 million legal defense fund for impacted drivers, as well as provide legal assistance and compensate their lost wages.

On Sunday, Lyft said it will donate $1 million to the ACLU over the next four years. Later in the day, Uber said it will create a $3 million legal defense fund for impacted drivers, as well as provide legal assistance and compensate their lost wages. Google is setting up a $2 million crisis fund: The search giant has set up a fund that will donate to the American Civil Liberties Union, Immigrant Legal Resource Center, International Rescue Committee, and UNHCR.

On Monday morning, former US Treasury Secretary Larry Summers, speaking in an interview with Bloomberg Television, said that he is “gratified” by what he heard from the tech community. “As global businesses, they have a huge stake in the United States being a nation of the Statue of Liberty rather than being a nation of refugee camps.” He added that “they have a huge stake in the United States supporting an open and tolerant global system, they have that stake for their employees, their customers, they have it for the reputation of the United States and they have spoken out.”

Donald Trump sitting down with tech CEOs during less turbulent times.

That may be, but the biggest reason for the anger by tech CEOs at the Trump administration is a simple, and a more selfish one. The reason for the simmering cold war between tech CEOs and Trump can be summarized in just three letters: H1-B. The bottom line is that tech CEOs fear Trump will single them out for outsourcing jobs or shut down the so-called H-1B visa program they use to hire high-skilled foreign employees for crucial engineering and technical jobs.

And, as Axios adds, White House officials say they are right to be nervous, especially about changes to the visa program. Chief strategist Steve Bannon and policy chief Stephen Miller are known to be deeply skeptical of the program, and will have a strong, vocal ally when Jeff Sessions gets confirmed as Attorney General. Some further observations:

Trump's mixed messages : On the campaign trail, he promised to "end forever the use of H-1B as a cheap labor program." He later signaled in a meeting with tech leaders that he's most concerned about companies misusing the visas to displace lower-wage American workers.

: On the campaign trail, he promised to "end forever the use of H-1B as a cheap labor program." He later signaled in a meeting with tech leaders that he's most concerned about companies misusing the visas to displace lower-wage American workers. How it works: Visas are capped at 65,000 a year, with 20,000 additional visas for foreign workers with master's degrees. The demand for the visas is so high that the cap is usually exceeded within a few days of the application window opening. The visas are distributed to companies through a lottery system.

Tech companies such as Microsoft, Google, IBM, Cisco, Apple, Intel and Facebook say the visas are crucial for specialized jobs they can't fill domestically because of a shortage of American graduates with the right technical skills. When CEOs spoke out over the weekend about the ban, they pointed out the importance of allowing the "best and brightest" to work in the U.S.

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Which is why if a news report about Trump's next imminent executive order is accurate, the simmering cold war between the tech CEOs and Trump is about to nuclear.

Bloomberg reports that the Trump administration has drafted an executive order aimed at overhauling the work-visa programs technology companies depend on to hire tens of thousands of employees each year. If implemented, the reforms could force wholesale changes at India companies such as Infosys Ltd. and Wipro Ltd., and shift the way American companies like Microsoft Corp., Amazon.com Inc. and Apple Inc. recruit talent. Companies would have to try to hire American first and if they recruit foreign workers, priority would be given to the most highly paid.

The draft of Trump’s executive order covers an alphabet soup of visa programs, including H-1B, L-1, E-2 and B1. The first is a popular program with technology companies and is aimed at allowing them to bring in high-skill workers when they can’t find local hires with the appropriate skills. The legislation caps the number of people who can enter the U.S. annually at 85,000, including those with undergrad and master’s degrees.

The average salary of an H-1B worker at Apple is reportedly more than $100k.

“Our country’s immigration policies should be designed and implemented to serve, first and foremost, the U.S. national interest,” the draft proposal reads, according to a copy reviewed by Bloomberg. “Visa programs for foreign workers … should be administered in a manner that protects the civil rights of American workers and current lawful residents, and that prioritizes the protection of American workers -- our forgotten working people -- and the jobs they hold.”

The foreign work visas were originally established to help U.S. companies recruit from abroad when they couldn’t find qualified local workers. But in recent years, there have been allegations the programs have been abused to bring in cheaper workers from overseas to fill jobs that otherwise may go to Americans. The top recipients of the H-1B visas are outsourcers, primarily from India, who run the technology departments of large corporations with largely imported staff. “If firms are using the program for cheap labor, I think it will affect them and they will have to pay workers more,” said Ron Hira, an associate professor at Howard University. “If tech firms are using the program for specialized labor, they may find there are more visas available.” The Trump administration did not respond to a request for comment on the draft. The proposal is consistent with the president’s public comments on pushing companies to add more jobs to the U.S., from auto manufacturing to technology.

It’s not clear how much force the executive order would have if it is signed by the president. Congress is also working on visa reforms and the parties will have to cooperate to pass new laws. Zoe Lofgren, a Democratic congresswoman from California, introduced a bill last week to tighten requirements for the H-1B work visa program.

"My legislation refocuses the H-1B program to its original intent – to seek out and find the best and brightest from around the world, and to supplement the U.S. workforce with talented, highly-paid, and highly-skilled workers,” Lofgren said in a statement.

Meanwhile, as Bloomberg adds, India’s technology companies, led by Tata Consultancy Services Ltd, Infosys and Wipro, have argued they are helping corporations become more competitive by handling their technology operations with specialized staff. They also contend the visa programs allow them to keep jobs in the U.S. and that if they have to pay more for staff, they will handle more of the work remotely from less expensive markets like India. Trump, however, see things differently.

“Inspections and investigations in the past have shown no cases of wrongdoing by Indian IT services companies, which have always been fully compliant with the law,” said R Chandrashekhar, president of Nasscom, the trade group for India’s information technology sector. “The industry is open to any kind of checks in the system, but they should not cause any hindrance to the smooth operation of companies. The proposed Trump order is also aimed at bringing more transparency to the program. It calls for publishing reports with basic statistics on who uses the immigration programs within one month of the end of the government’s fiscal year. The Obama Administration had scaled back the information available on the programs and required Freedom of Information Act requests for some data. Whatever specific changes are implemented, they are likely to add to the expenses for India’s technology companies. That may accelerate a shift to new kinds of services, such as cloud computing and artificial intelligence, said Raja Lahiri, partner at the Mumbai-based partner at consultancy Grant Thornton India

“The visa challenges are not going to go away easily,” he said. “They will continue to be a challenge for Indian IT companies.”

But while the pain for India will be acute, it will be Silicon Valley that may be most impacted, as suddenly its favorite source of cheap, skilled labor is eliminated. How it will responds remains to be seen.