The warning comes after Chinese Coast Guards captured and damaged two Philippine ships last month, injuring military soldiers on a resupply run to a Shoal outpost, according to Philippine officials.
Manila claims that China has been attempting to disrupt resupply operations to a Philippine ship stationed on the Shoal since 1999. Both countries claim the island, but the ship's presence has strengthened Manila's maritime rights.
The most recent flare-up saw an increase of violence, with Chinese Coast Guard members wielding knives and axes against their Filipino colleagues.
"Under the Rules of Engagement (ROE), an individual has the right to defend himself in any way... So, for example, if someone attacks, we will use the same amount of force as we would use to protect ourselves," Brawner said following a meeting with President Ferdinand R. Marcos Jr.
According to Brawner, this proportionality means that if Filipino troops are assaulted with knives, they will defend themselves with similar weapons rather than resorting to excessive force like shooting.