Engel noted that Russia recently gifted Serbia $600 million worth of weapons, including six MiG-29 'Fulcrum' fighter jets, 30 T-72 tanks and 30 BRDM-2 armored reconnaissance vehicles.
The congressman from New York State added that Serbia is now seeking Russian-made S-300 air defense systems.
"Frankly, I'm growing increasingly concerned with the choices Belgrade is making on military and security matters," Engel said. "This is why I wrote today's amendment."
Engel explained the United States needs to take a closer look at Russian-Serbian military ties and judge their implications for US national security policy, Serbia's membership in NATO's Partnership for Peace as well as the impact on its neighbors.
Engel added that Vice President Mike Pence's upcoming meeting with Serbian President Aleksandar Vucic on Monday would be a good opportunity to raise US concerns about Belgrade's direction on security policy.