March 8 (UPI) -- President Donald Trump began to outline his $1 trillion infrastructure proposal during a meeting at the White House on Wednesday, including exploring an experimental form of super high-speed transportation envisioned by entrepreneur Elon Musk.
Trump conducted the meeting with 13 federal agencies that would play a role in the infrastructure plan, from the agencies tasked with evaluating proposals and doling out money to those that would oversee specific projects.
The Wall Street Journal, which was permitted to attend the private advisory session between Trump and top economic and manufacturing advisers, reported that he reiterated previous statements that federal money would leverage private investment to help fund the overall proposal.
According to the Journal, Trump also expressed a preference for renovating existing infrastructure, like roads and bridges, versus building new projects. He also said his administration would not approve projects unless states could demonstrate their ability to begin construction within 90 days to avoid spending money for plans that get tied up in red tape.
"We're not going to give the money to states unless they can prove that they can be ready, willing and able to start the project," Trump said, according to the Journal. "We don't want to give them money if they're all tied up for seven years with state bureaucracy."
Among the most prominent private sector attendees at Wednesday's meeting was Musk, the billionaire co-founder of PayPal, who has gone on to several leading edge technological projects -- including a private space mission and electric automaker Tesla.
Musk is behind a broad strokes proposal to revolutionize mass transit with a high-speed rail system known as Hyperloop -- a concept aimed at transporting people in "pods" at speeds of more than 700 mph through underground tubes, using vacuums as a power source.
Trump did not address Hyperloop specifically, but said he favors high-speed rail projects as part of his $1 trillion plan.