WASHINGTON, April 16 (Xinhua) -- U.S. President Donald Trump on Thursday unveiled guidelines for a phased reopening of parts of the U.S. economy disrupted by the COVID-19 pandemic.

"Our experts say the curve has flattened, and the peak in new cases is behind us. Nationwide more than 850 counties or nearly 30 percent of our country have reported no new cases in the last seven days," Trump said at a White House press conference.

"Based on the latest data, our team of experts now agrees that we can begin the next front in our war, which we are calling 'opening up America again,' and that is what we are doing," he said.

Trump noted that a national shutdown is not a sustainable long-term solution, and a prolonged lockdown, combined with a forced economic depression, would "inflict an immense and wide-ranging toll" on public health.

"Therefore my administration is issuing new federal guidelines that will allow governors to take a phased and deliberate approach to reopening their individual states," said the president.

The criteria for reopening the economy include showing a downward trajectory of COVID-19-like symptoms reported over 14 days in a given state or region, as well as a decline in documented cases or positive tests during the same 14-day window, according to the guidelines.

The states and regions should also ensure that hospitals can treat all patients, and have a robust testing program in place for at-risk healthcare workers before moving to the phased reopening.

The goal of the guidelines is to mitigate the risk of a resurgence in cases and protect vulnerable populations, according to the White House. State and local officials may need to tailor the application of these criteria to local circumstances.

"We are not opening all at once but one careful step at a time, and some states will be able to open up sooner than others," said Trump.

The guidelines came after the Federal Reserve said Wednesday that economic activity "contracted sharply and abruptly" across all regions in the United States as a result of the COVID-19 pandemic.

The number of COVID-19 cases in the United States topped 660,000 as of Thursday evening with more than 32,000 deaths, according to the Center for Systems Science and Engineering at Johns Hopkins University.