President Ferdinand R. Marcos Jr. and US Vice President Kamala Harris (PNA photo by Rey Baniquet)

MANILA – The 1951 Mutual Defense Treaty between the Philippines and the United States (US) remains under "negotiation and evolution," President Ferdinand R. Marcos Jr. said Thursday.

"Well, the Mutual Defense Treaty is continuously under negotiation and under evolution. I always call it as an evolution because things are changing," Marcos said in a media interview on the sidelines of the Kadiwa ng Pasko caravan in Quezon City.

Marcos' statement came after National Security Adviser Secretary Clarita Carlos earlier revealed that the President ordered a scrutiny of MDT.

Marcos said the defense pact between the two countries are under review because the US has "many requests and proposals," particularly in the 2014 Enhanced Defense Cooperation Agreement (EDCA).

"So all of that is under study now to see what is really feasible and what will be the most useful for the defense of Philippine territory," he said.

Concerns on security and defense cooperation between the two nations were among those tackled during a recent meeting with US Vice President Kamala Harris, Marcos said.

"We covered that and many more subjects. But essentially, on the security, ‘yun tinitingnan natin ‘yung kanilang pino-propose, ‘yung mga joint exercises (we are studying their proposal, the joint exercises), and EDCA, the use of our bases, all of these. We are in the middle of that," Marcos said.

During their meeting at Malacañan Palace on Nov. 21, Harris assured Marcos that the US would "always" stand with the Philippines in defense of international rules and norms as it relates to the highly-contested South China Sea (SCS).

Harris also stressed that any possible armed attack against Philippine forces in the SCS would prompt the invocation of US mutual defense commitments.

The 1951 MDT, the longest-running defense pact, aims to step up the defense and security cooperation between the Philippine and US troops.

Carlos on Nov. 22 said that the government has already created a group to study and review the MDT.

The group, Carlos said, is composed of officials from the National Security Council, the Department of National Defense and the Department of Foreign Affairs. (PNA)