There are many possible causes for an employee's performance and/or conduct problem, for example, illness, disability, drug or alcohol abuse, personality conflict, family problems, lack of training, low job morale, etc. The nature of the problem will determine the course of action to be taken. Maybe the employee should be referred to the Employee Assistance Program for substance abuse counseling, or a fitness-for-duty medical examination may be needed to determine physical or mental capability to do the job.
If the problem is failure to meet the objectives/responsibilies he/she has established on the DA Form 7222-1 (Support Form in the Senior System) and DA Form 7223-1 (Counseling Checklist in the Base System) - Performance Plan, then appropriate action could be taken under the Performance Management Program. For guidance on dealing with poor job performance refer to menu item Management-Employee Relations Program - Dealing With Poor Performers.
If it is misconduct or delinquency, such as tardiness, falsification of travel vouchers, misuse of government property, failure to properly request leave, insubordination, theft, etc., then the supervisor's option could be to take disciplinary action. He/She has a variety of ways to deal with these, depending on the severity of the misconduct: lesser disciplinary actions, such as admonishments and reprimands, to more severe penalties, such as suspensions and removals.
There may be instances where the problems are both performance and conduct. In these cases, supervisors could take action under either program.