US Secretary of State John Kerry was expected to meet with Belgian leaders on Friday after terrorist attacks earlier this week rocked the seat of the European Union's main institutions.
Investigations into the attacks, which left at least 31 dead and 300 injured, are ongoing.
Heavy criticism has been levied against European security policy in the run-up to the attacks. Ministers from across Europe gathered in Brussels on Thursday to press for better cooperation on key tactics like data sharing.
Six people were detained late Thursday in police raids, and RTBF state broadcaster reported another arrest that took place during a police search on Friday morning in the neighborhood of Forest, where a shootout last week led investigators to key Paris attacks suspect Salah Abdeslam.
Kerry's visit is intended to, "reiterate the strong support of the US for Belgian efforts to both investigate these attacks and continue contributing to international efforts to counter violent extremism," his office said.
The secretary is expected to lay a wreath at a memorial to the attack victims, before meeting with European Commission President Jean Claude Juncker, Belgian Prime Minister Charles Michel and Interior Minister Jan Jambon.