FAA Grant Assurance #20 in the Airport Sponsor Assurances states that "It (meaning the airport sponsor) will take appropriate action to assure that such terminal airspace as is required to protect instrument and visual operations to the airport (including established minimum flight altitudes) will be adequately cleared and protected by removing, lowering, relocating, marking, or lighting or otherwise mitigating existing airport hazards and by preventing the establishment or creation of future airport hazards."

To what extent should a municipality go to if a land owner refuses to allow the airport to remove trees or other obstructions from the owner's property? Assume for argument sake, that the trees are considered "hazards to navigation" and without their removal, the airport's approach minimums must be raised. What can airports or municipality do proactively to prevent this from happening again with other homeowners?

Support your answer with research and include a citation of your research in your response.