New York, Washington, London and Paris are among the world cities where security has increased following Tuesday's apparent terror attacks in Belgium.
Thousands of miles from the chaos in Belgium, American cities have ramped up security in the wake of Tuesday's apparent terror attacks in Brussels.
Dozens are reported dead and well over 100 were reportedly injured after twin blasts rocked the Brussels Airport and a city subway station on Tuesday morning.
News of the tragedy was a call to action for anti-terrorism forces in European capitals and beyond in New York City and Washington, DC.
Read: Paris Terror Suspect On The Run Arrested in Belgium: 'We Got Him'
The NYPD released a statement Tuesday morning about beefing up resources across multiple teams.
"[We are] closely monitoring the situation in Belgium and is in close contact with our international partners and with the FBI," the statement read.
"Until we learn more, the department has deployed additional counterterrorism resources across the city including: the Counterterrorism Response Command (CRC), the Strategic Response Group (SRG), and Hercules Teams."
These teams were deployed to crowded areas, including major transit hubs in and around the city "out of an abundance of caution," according to the release.
Read: Dozens Reported Dead, More Than 100 Injured in Multiple Explosions in Brussels
In America's capital, Metropolitan Area Transit Authority in Washington said it was carrying out K-9 sweeps and increased patrols.
A WMATA tweet, however, said there was "no credible threat" to Washington, DC.
President Obama, who is in Cuba for a third day, was briefed about the explosions Tuesday morning in Havana and expected to address the situation in a speech from the Caribbean island.
Security expert Bill Stanton says any time you find yourself in a terminal, airport or mall, figure out ahead of time how to escape in an emergency and not the exits.
He also said that if you see something peculiar such as a nervous traveler or someone who drops a bag on the ground and walks away, alert the authorities.
“It is that age old cliché, ‘if you see something, say something,’” he said.
Terrorism expert Robert Strang says ISIS may be focused on Europe for now but a similar attack could happen here any time.
“We try in the us to keep a little bit more information on people who are coming into our country but to be honest we don't know everyone who is in our country so we also have this potential problem as well,” he said.
Watch: President Obama Lays White Rose for Paris Victims
