The president of Venezuela's National Congress, Juan Guaidó. Photo: Roman Camacho/SOPA Images/LightRocket via Getty Images

Venezuelan authorities released opposition leader and congressman Juan Guaidó after briefly detaining him on Sunday while he was en route to an anti-government political rally, per AP.

Why it matters: His brief detention comes just days after President Nicolás Maduro assumed power for a second six-year term, which the U.S. government said it will not recognize. Guaidó has been mounting a campaign to oust Maduro, and White House national security adviser John Bolton highlighted his work in a statement Friday: "We support the courageous decision of the National Assembly President, Juan Guaidó, to invoke protections under Venezuela’s constitution and declare that Maduro does not legitimately hold the country’s presidency."

Go deeper: The grim list of problems Venezuela faces in Maduro's 2nd term

Go deeper

The hacking of Iran's hackers

Illustration: Aïda Amer/Axios

An Iranian cyber operations front organization that’s a target of new U.S. sanctions was itself the victim of an attack that looted its own hacking tools and dumped them on the internet two years ago.

Driving the news: Last week, amid increasing tensions between Washington and Tehran, the Treasury Department announced major new Iran-related sanctions targeting cyber operators working for Iranian intelligence. The sanctions targeted 45 individuals affiliated with Iran’s Ministry of Intelligence and Security (MOIS), Tehran’s main civilian intelligence agency.

FDA chief vows agency will not accept political pressure on coronavirus vaccine

Food and Drug Administration Commissioner Stephen Hahn promised that "science will guide our decision" for a coronavirus vaccine at a Senate hearing on Wednesday.

Why it matters: More Americans are expressing doubt about a first-generation vaccine, despite President Trump's efforts to push an unrealistic timeline that conflicts with medical experts in his administration.

CEO confidence rises for the first time in over 2 years

Data: Business Roundtable; Chart: Naema Ahmed/Axios

A closely-watched CEO economic confidence index rose for the first time after declining for nine straight quarters, according to a survey of 150 chief executives of the biggest U.S. companies by trade group Business Roundtable.

Why it matters: The index, which still remains at a decade low, reflects corporate America's expectations for sales, hiring and spending — which plummeted amid uncertainty when the pandemic hit.

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