Security at major American cities along with public places like airports, train stations and shopping malls was today enhanced with additional layers of screening, in the aftermath of the horrific terrorist attack in Brussels that killed about 35 people.
Security has been in particularly beefed up here in the US Capital, which would host Nuclear Security Summit later this month that would bring in heads of States from over 40 countries.
Officials said there was no specific security threat to any major US cities, but as a matter of precautionary measure security agencies began performing additional sweeps and patrols.
In a statement, the Metropolitan Washington Airports Authority said the Reagan National and Dulles International have robust security, both visible and behind-the-scenes and the authority's priority is the safety and security of passengers and employees.
New York Governor Andrew Cuomo said he has directed state law enforcement officials to step up security at high-profile locations around the state, including airports, bridges, tunnels and mass transit systems.
However, he insisted, there is no known credible threat to the state at this time and the federal threat level has not been elevated now.
The New York Police Department (NYPD) said it has deployed additional counterterrorism resources across the city.
"Teams have been deployed to crowded areas and transit locations around the city out of an abundance of caution to provide police presence and public reassurance as we closely follow the developing situation overseas," said NYPD Deputy Commissioner Stephen P Davis.
New York City Mayor Bill de Blasio said that the city residents should expect to see extraordinary NYPD presence out over the coming days as a sign of its readiness to protect people at all times.
In a statement, Los Angeles International airport said it has increased visibility of police officers.
Chicago Mayor Rahm Emanuel said while there is no immediate threat to Chicago, the city will be on alert to keep residents safe.
Amtrak, which runs the largest passenger train network in the country, said it is partnering with local law enforcement to keep the railroad and train stations safe.
Officials have asked riders to tell authorities about any unattended items or suspicious behaviour.
Several US airlines including United and American airlines announced to have suspended it flights to Brussels.
"While there are no credible threats at this time in our area, we are asking all officers to pay close attention to transit locations throughout the city," the police said in a statement.
