The Philippines says it may need to review a longstanding defense treaty with the US. The move follows increasingly contentious encounters with Beijing in the South China Sea.

Philippine National Maritime Council spokesperson Alexander Lopez said on Wednesday that the Mutual Defense Treaty was signed in 1951, and since then, the strategic landscape has changed so much. He said that maybe it's high time now to make a review.

The treaty obliges Washington to defend Manila in the event of an armed attack against its ships and aircraft.

Lopez's remarks come after Philippine Defense Secretary Gilberto Teodoro said the treaty must be interpreted more broadly for a "dynamic and cunning adversary."

Admiral Samuel Paparo, the head of the US Indo-Pacific Command, said that every option between the two sovereign nations in terms of their mutual defense, and escort of one vessel to the other, is an entirely reasonable option within their Mutual Defense Treaty among this close alliance between the two.

In one recent incident, the Philippine government accused Chinese vessels of obstructing a mission to resupply Filipino fishermen with fuel and food in the South China Sea. China said the coast guard ship was implementing laws in a normal way.