Thitu Island, which is known in the Philippines as Pag-asa, is the second largest of the naturally-occuring Spratly Islands. Although it has been administered as part of the Philippines' Kalayaan municipality since June 1978, the disputed island is also claimed by China, Taiwan and Vietnam.
The Philippines' Department of Foreign Affairs said in a release that "the presence of Chinese vessels near and around Pag-asa and other maritime features in the KIG [Kalayaan Island Group] is illegal."
"Such actions are a clear violation of Philippine sovereignty, sovereign rights and jurisdiction, as defined under international law including the 1982 United Nations Convention on the Law of the Sea (UNCLOS)," the statement reads.
"Moreover, it has been observed that Chinese vessels have been present in large numbers and for sustained and recurring periods — what is commonly referred to as ‘swarming' tactics — raising questions about their intent as well as concerns over their role in support of coercive objectives."
"Such actions when not repudiated by the Chinese government are deemed to have been adopted by it. The presence of Chinese vessels within the KIG, whether military, fishing or other vessels, will thus continue to be the subject of appropriate action by the Philippines," it added.
The statement was followed by remarks from Philippine President Rodrigo Duterte, who said in a recent speech that China needed to "lay off" the disputed islands, adding that Filipino troops would be deployed if Beijing touches Philippines' territory, Reuters reported.
"I will not plead or beg, but I am just telling you that lay off the Pag-asa because I have soldiers there," Duterte said. "If you touch it, that's a different story. I will tell the soldiers ‘prepare for [a] suicide mission.'"
He also indicated that he wouldn't allow Beijing to occupy the island because it belongs to the Philippines. A 2016 Hague decision also found that Beijing had no historical right to territories within its "nine dash line" it uses to define its sweeping claims in the sea.
Within just the first three months of 2019, more than 200 Chinese vessels have been spotted around the island, according to officials. Satellite imagery published in February by the Asia Maritime Transparency Initiative (AMTI) found that during its observations of the hotly contested waters, nearly 100 Chinese vessels were stationed near Thitu. AMTI's report noted that the Chinese fleet was mostly composed of vessels from the People's Liberation Army-Navy, China's Coast Guard and fishing ships, Sputnik previously reported.
"This deployment is consistent with prior examples of China's ‘cabbage strategy,' which employs concentric layers of fishing, law enforcement and naval vessels around contested areas," the report states.
Jeffrey Ordaniel, assistant professor of International Securities Studies at the Tokyo International University and a fellow at the Pacific Forum International, told Sputnik Thursday that there's a paradox in the Philippines, as "the defense and foreign policy establishments in Manila remain torn between advocating for the country's national interest in the South China Sea… and accommodating Duterte's parochial concern of not offending Beijing at all cost."
"The Duterte administration is facing mounting political pressure to respond to the growing number of Chinese fishing vessels around Thitu Island," he said. "Many in the Filipino government have finally expressed serious doubts on Duterte's preferred China policy. Beijing wants Manila to be less deferential to Washington and to downplay the 2016 Arbitration Ruling. Yet, despite Duterte repeatedly doing those, Beijing has yet to show any indication that it is open to compromise on the South China Sea issue."
While Chinese Foreign Ministry spokesperson Geng Shuang failed to speak to directly on the issue of the Thitu Island, he did recently tell reporters that talks between Chinese and Filipino officials on Wednesday were "frank, friendly and constructive."
Duterte has largely maintained warm relations with China since taking office in 2016 in exchange for promised investments worth billions of dollars.