Rubio’s remarks came as the region is grappling with a series of overlapping claims by China and ASEAN member states in the South China Sea, another crucial maritime route for global trade.
His arrival in the Philippines on Tuesday morning coincided with the US condemnation of a recent clash between Chinese and Philippine sailors in the disputed waterway.
Rubio is to meet his Chinese counterpart Wang Yi on Wednesday on the sidelines of the ASEAN summit, where he will also have talks with fellow Quad members India, Australia and Japan, and others.
The secretary of state added that the United States remains „open“ to diplomacy with Iran but that Tehran is not „serious“.
„The United States remains open and willing to engage in positive and constructive negotiations and discussions, provided that the commitments made are honoured,“ he said.
„The problem we are currently facing is that they are not taking the negotiations seriously,“ Rubio said.
„If they are serious, we will be too. If they are not, then we will do what is necessary to protect our interests and those of our allies.“