The two military police members tested positive for opioids on Sunday. They are believed to have obtained the substance while on authorized leave from the barracks.
"Two Croatian Army members will be disciplined and removed from service", the Ministry said in a statement.
They will be sent back to Croatia immediately, the Ministry added, stressing that it has zero tolerance for 'non-military' behavior, such as abuse of intoxicating substances, and will punish it harshly.
The Enhanced Forward Presence initiative was adopted on the 2016 Warsaw Summit to boost NATO’s military presence in the eastern part of the Alliance. As of now, four multinational battalion-size battlegroups in Estonia, Latvia, Lithuania, and Poland, have been deployed on a rotational basis.