(L-R) Secretary of Defense Mark Esper and Chairman of the Joint Chiefs of Staff Army Gen. Mark Milley hold an end of year press conference at the Pentagon on December 20, 2019 in Arlington, Virginia.

WASHINGTON — The Pentagon's top leaders said Tuesday that they were planning for the coronavirus pandemic to plague the United States for months.

"I think we need to plan for this to be a few months long at least and we're taking all precautionary measures to do that," Secretary of Defense Mark Esper said during a virtual town hall from the Pentagon.

Alongside Esper, the nation's top military officer said that while it was unclear how long the deadly outbreak would last, he gave an estimate of up to three months.

"You're looking at eight to 10 to 12 weeks, call it three months, based on what we know from other countries like China, Hong Kong, South Korea, etc., that may or may not apply to the United States," Chairman of the Joint Chiefs of Staff U.S. Army Gen. Mark Milley said.

At the same time as the military brass expressed their expectations, President Donald Trump said Tuesday that he wants the U.S. economy to "open" back up by Easter Sunday, even as the number of confirmed coronavirus cases in the country accelerates.

Easter is April 12, less than three weeks away.

Trump's remarks in a Fox News "virtual town hall" event at the White House came as more states imposed extreme measures, including shutting down businesses and ordering residents to stay home, to try to slow the spread of the disease.

The virus has infected more than 398,000 worldwide, though many have recovered. In the U.S. more than 46,500 cases have been reported so far.

On Tuesday, the number of active-duty U.S. service members who have tested positive for the coronavirus jumped from 133 to 174 overnight, according to the latest figures provided by the Pentagon. As of Tuesday, the Pentagon has a total of 321 cases, 174 are active-duty military, 59 are civilians, 61 dependents and 27 contractors.

Over the weekend, the Department of Defense confirmed that a contractor, who worked at the Defense Security Cooperation Agency, died on Saturday after testing positive for the coronavirus. This is the first reported death from the virus within the DOD.

-- CNBC's Kevin Breuninger contributed to this article.