The NYPD has beefed up security at locations including the Empire State Building, World Trade Center site and houses of worship in the wake of online "chatter" about terror threats.
The State Department says the "chatter" prompted U.S. officials to keep diplomatic posts in some 19 cities in the Mideast and Africa closed through at least the end of this week.
Government officials are calling this one of the most credible threats they've seen in years.
Officials say the threats are not necessarily against targets in New York or elsewhere in the U.S., but as is normally the case when there is any kind of terrorism threat, the NYPD is being extra vigilant.
Egypt and Yemen are just two of the countries where American embassies have been shuttered today, amidst warnings that al-Queda or its affiliates might be planning an attack.
In all, embassies in 22 countries have been closed and now 19 will remain closed through at least Saturday out of what the State Department is calling an abundance of caution.
"We're on a high state of alert. I have been given every assurance that we're doing everything we can to prevent this threat from happening. This is one of the most specific and credible threats I've seen since 9-11," said Rep. Mike McCaul, (R-TX).
"This specific threat that we've been briefed on over and over again has reached a new level," added Sen. Dick Durban, (D- IL).
While intelligence officials don't know specifics of when or where an attack might be carried out, they're taking no chances. The State Department has issued a global travel alert.
Former FBI agent and NYPD Sergeant Manny Gomez explains why.
"The alert is for people traveling to these countries, the Arabian Peninsula, the Middle East, Israel, these sorts of countries, if they're already there the best advice is to stay away from high profile target locations."
In New York, the NYPD has stepped up security at high profile targets including some embassies and houses of worship.
"Whenever we get any indication, New York will always spike up its attention internally," said Gomez.
While many New Yorkers are aware of the threat, most say they are carrying on as usual.
"Nothing that has been any definitive difference at all," said one resident.
"We were here for 9-11, so I guess we've been through the worst so far, hopefully nothing like that will happen again," added another.
The world travel alert is the first of its kind to be issued by the State Department since the 10th anniversary of the 9-11 attacks – it will be in effect until the end of August.
The department says U.S. citizens planning to travel to the Middle East or Arabian Peninsula should register their plans with the U.S. Embassy in advance.