Security was stepped up at the US airports and transit systems even as authorities said they have not found any plan for an attack similar to Tuesday's bombings at Zaventem airport and a Metro station in Brussels.
Department of Homeland Security Secretary Jeh Johnson said on Tuesday that no credible or specific intelligence regarding a similar plot has been uncovered, The Washington Times reported.
"That said, we remain very focused on the threat posed by lone terrorist actors who may lack direct connection to a foreign terrorist organisation," Johnson said in a statement.
"We also remain very engaged in the effort to identify and disrupt foreign terrorist fighters who may seek to travel to or from the US," he said.
He confirmed that the FBI has been in communication with state and local law enforcement, to share the latest about what they know of attacks in Belgium.
In the statement, Johnson asserted that since the Paris attacks in November the officials have enhanced information sharing about potential terrorist threats with both Belgian and French authorities.
"Though the US does not require Belgian citizens to have a visa to travel here for business or tourism purposes, both the Transportation Security Administration (TSA) and Customs and Border Protection (CBP) have procedures in place to identify and prevent travel here from Belgium by individuals of suspicion," Johnson said.
"All travelers arriving in the US are vetted against the US Terrorist Screening Database, regardless of whether they arrive with a visa or an Electronic System for Travel Authorization (ESTA)," he said.
As a precautionary measure, Johnson said that TSA is deploying additional security to major city airports in the US, and at various rail and transit stations around the country. "TSA is also working closely with state and local law enforcement, airport and transit authorities, and the aviation industry in order to augment that security," he said.
Despite the explosions that rocked the Belgian capital, Homeland Security officials said they were not issuing any new terror intelligence bulletins or revising the terror alert level in the US.
Meanwhile, US President Barack Obama in a proclamation ordered for the US national flag to fly at half-staff to honour the victims of the Brussels terrorist attack.
At least 34 people were killed and over 200 injured in a series of explosions at the main airport and in a Metro station of Brussels on Tuesday.
With inputs from agencies