Ships have in the past gone into the area without approval from Manila, triggering warnings from the Southeast Asian country’s defence chief. The vessel called Ke Xue that arrived in the Philippines this week ahead of an approved mission to a strategically crucial undersea region sparked concerns over the Southeast Asian country’s powers of jurisdiction, and its national security. Seven leftist party-list lawmakers belonging to the Maka­bayan bloc want the House of Representatives to look into the government-approved Chinese maritime research in Benham Rise. Unapproved sailings by Chinese ships in the undersea region triggered a stern warning from the Philippines’ Defence Secretary Delfin Lorenzana in March last year, saying he was “disturbed” by what he believes are survey missions by Chinese ships.