MANILA - A Chinese survey ship that was seen earlier this month sailing east of the Philippines was spotted once again inside the Philippine exclusive economic zone (EEZ), maritime experts have confirmed.

Chinese oceanographic survey ship “Zhangjian” entered the Philippines’ EEZ, said Ryan Martinson, Assistant Professor of the Chinese Maritime Studies Institute at the US Naval War College who posted the ship’s position on Twitter.

The Chinese oceanographic survey ship "Zhangjian" has returned to the Philippines exclusive economic zone. Heading west at 10 knots. https://t.co/nrzykbNUCK pic.twitter.com/kLVQGQekEt

— Ryan Martinson (@rdmartinson88) August 21, 2019

Professor Jay Batongbacal, Director of the UP Institute for Maritime Affairs and Law of the Sea, and Jess Floren of the Karagatan Patrol confirmed the ship’s presence in the country’s EEZ.

The survey ship Zhangjian was tracked making grid-like, back-and-forth movements in the Philippine Sea for days, a movement the experts suggest was indicative of scientific exploration.

The grid-like maneuvers, however, took place just outside the Philippines’ EEZ, which is not violative of Philippine maritime rights.

However, the tracks reveal that after surveying in the high seas, the Zhangjian moved westward in a straight path towards the Philippines, and on August 20 entered the Philippines’ EEZ a little north of Catanduanes.

The Zhangjian then moved southward along the Philippines’ eastern coastline, and as of August 23 it was still within the EEZ off the coast of Samar.

The path taken by the Zhangjian was similar to what it took in early August, when Martinson said in a tweet that it operated just 80 nautical miles off the Philippines’ eastern coast.

Defense Secretary Delfin Lorenzana confirmed that Manila was aware of the Chinese survey ship’s presence. He said the Chinese ship did not seek clearance from Filipino authorities to enter the EEZ.

Lorenzana, however, said Manila has not raised alarm about the ship’s presence.

“Karamihan naman ng area niya is outside our EEZ eh, doon sa Pacific Ocean, kaya lang paminsan dumadaan sya dito. Hindi naman siya nagtatagal eh,” said Lorenzana.

(Most of the areas where it had presence were outside our EEZ, in the Pacific Ocean. Sometimes it enters the EEZ but it did not linger.)

“Pero pagka dumaan lang sila sa atin siguro, iikot siya, medyo siguro may iniiwasan siyang mga alon d'yan o whatever, weather, then I think it’s okay, huwag lang silang magtagal dun sa ating EEZ,” said Lorenzana, who had earlier complained of the unauthorized passage of Chinese warships in Philippine waters.

(If the ship entered the EEZ, perhaps it was avoiding strong waves or some weather disturbances, then I think that’s okay as long as it does not linger within our EEZ.)

• READ: Why the secrecy? Lorenzana flags passage of 9 Chinese warships through PH waters

Asked whether Manila should be worried that China was already mapping out the eastern Philippine seabed, Lorenzana said: “That will be a concern but we don’t know what they are doing. They might just be studying the current, or the sea… It’s premature to say they are surveying.”

Batongbacal, meanwhile, believes the ship was continuing the oceanographic research that has been carried out by the Chinese for the past few years.

“The north-south movement is probably meant to monitor the conditions of the currents from the Pacific going west toward the Philippines,” Batongbacal said.

Batongbacal also believes that the Zhangjian’s study is relevant to the Philippines.

“The currents influence weather above and sea conditions below, which affect fisheries and biodiversity. Thus, the research has relevance to Philippine EEZ rights,” Batongbacal said.

“Even if much of the voyage appears to be outside the EEZ, at least part of it occurs within.”

The Philippines has filed several diplomatic protests against China over its ships’ passage through Philippine waters without informing Filipino authorities.

• PH fires off another diplomatic protest over Chinese warships

Under the United Nations Convention on the Law of the Sea, any foreign vessel may be allowed to cross a coastal state’s territorial waters without notifying the state if they are conducting innocent passage, or movement in a straight path heading back out to sea.

On Tuesday, President Rodrigo Duterte said all foreign vessels passing through Philippine waters need to secure prior clearance from the government.

• PH requires passing foreign vessels to seek clearance

Maritime rights is a sensitive issue for both the Philippines and China, which are locked in a bitter dispute over the South China Sea.

China claims large parts of the South China Sea through which roughly $3.4 trillion in goods pass each year. Claimants including Malaysia, the Philippines, Taiwan and Vietnam contest the territorial claims.

It has ignored a landmark Philippine victory before a United Nations-backed arbitral tribunal that invalidated its sweeping 9-dash line claim to nearly all of the resource-rich waters.

China has unnerved the region and angered the United States by installing military equipment and other facilities on artificial islands it has made by reclaiming land and building up reefs and shoals.

– With a report from Reuters