Trump had said earlier in the week he would tap the act as needed. He said Friday he has put that "in gear."
Trump also announced an effective closure of the U.S. border with Mexico, prohibiting most travel except for trade. That brings it in line with the restriction on the Canadian border earlier this week. The U.S. is also suspending interest on student loans to help young people cope with job losses and the financial crunch.
More than 200 people have died from COVID-19 in the U.S. and sickness from the disease is on the rise, with hospitals at risk of being overrun. Most people who get it have only mild or moderate symptoms, such as fever and cough. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia.
Senate Democratic Leader Chuck Schumer said he implored Trump during a phone call Friday to invoke the Korean War-era act immediately to order the manufacture of ventilators and other critically needed medical gear. The president told Schumer he would, then could be heard on the telephone seeming to make the order. He yelled to someone in his office to do it now, said Schumer's spokesman, Justin Goodman.
The president and the Cabinet officials who briefed reporters focused on the border as they moved to restrict the entry of people without documentation to the U.S. This follows a stepped-up State Department travel advisory telling Americans they should not leave the country.
As Congress debated a financial relief package that could reach $1 trillion, officials again urged Americans to maintain social distancing while Dr. Anthony Fauci, the nation's top infectious disease expert, applauded strict new measures put in place by the governors of California and New York to limit mobility.
Trump and Fauci broke openly during the White House briefing on the possible effectiveness of new drugs being explored to treat the virus. Trump said he believed that a combination of medications he announced Thursday would would work to treat the virus. Fauci said no such declaration could be made without testing.
On another front, Trump said the Education Department will not enforce standardized testing requirements for students in elementary through high school for the current year. Under federal education law, states are required to administer standardized tests every school year.
"Americans from every walk of life are coming together," Trump said. "We are winning and we are going to win this war."
But the task force briefing Friday turned contentious. At one moment, the president, when asked what message he would have for frightened Americans watching at home, Trump responded, "I think you are a terrible reporter."
The new measures come as the administration tries to overcome its inability to provide the needed masks and ventilators to hospitals on the verge of being overwhelmed by coronavirus patients.
On Capitol Hill, lawmakers have been working toward an aid package to prop up households and the U.S. economy that would put money directly into American's pockets.
According to the World Health Organization, people with mild illness recover in about two weeks, while those with more severe illness may take three to six weeks to recover.
The Associated Press receives support for health and science coverage from the Howard Hughes Medical Institute's Department of Science Education. The AP is solely responsible for all content.