Read the following text and answer the question.

In the context of modern policing, the concept of community-oriented policing (COP) has gained significant traction. COP emphasizes proactive problem-solving and building partnerships between police and the community. However, a recent study published in the Journal of Police Studies examined the implementation of COP in a mid-sized Brazilian city and found that while officers received training on the principles of COP, many struggled to apply them in practice due to deeply ingrained reactive mindsets. The study highlighted that officers often reverted to traditional enforcement methods when faced with high-pressure situations, such as responding to violent crimes. The researchers concluded that for COP to be effective, it requires not only training but also a cultural shift within police organizations, supported by continuous evaluation and community feedback.

According to the text, what is the main obstacle to the effective implementation of community-oriented policing (COP) as identified by the study?