Person trying to claim adverse possession

[skybizzer]

I live in Arkansas and just purchased 40 acres. There is a state highway going between the property with 4.5 acres on one side of the highway. The person who owns the surrounding property has at some time put up a fence and a gate and is using it for pasture. Since we purchased the land the person is claiming ownership and refuses to unlock the gate and give us access. (The entrance road is on our property.)What can we legally do?
Thanks

 

[HomeGuru]

Give advance notice then if no action cut the lock and remove the gate.