The Maritime Self-Defense Force will hold joint military exercises with five Asian navies and the U.S. during a rare long-term dispatch to the South China Sea and Indian Ocean, the Defense Ministry’s Maritime Staff Office has said, in a move certain to stoke anger in Beijing.

Japan announced Tuesday that it will send three vessels — including its largest, the helicopter destroyer Kaga — for a more than monthlong tour set to begin Sunday and run through October.

The three ships will make port calls in India, Sri Lanka, Singapore, Indonesia and the Philippines, and will conduct joint exercises aimed at bolstering combat skills and improving cooperation with each country’s navy while also linking up with the U.S. Navy.

Tuesday’s announcement also came on the same day that defense chief Itsunori Onodera pledged to help strengthen Sri Lanka’s maritime security, in a fresh sign of efforts to counter China’s strategic grip on the Indian Ocean island.

President Maithripala Sirisena thanked Onodera — the first Japanese defense minister to visit the country — for donating two coast guard patrol craft costing over $11 million in total, his office said in a statement after talks in Colombo.

Beijing has built up a series of military outposts in the South China Sea, which includes vital sea lanes through which over $3 trillion in global trade passes each year. China claims the area within its so-called nine-dash line, which encompasses most of the waterway. The Philippines, Vietnam, Malaysia, Taiwan and Brunei have overlapping claims.

China has said the facilities are for defensive purposes, but some experts say this is part of a concerted bid to cement de facto control over the South China Sea.

Media reports quoted Japanese government sources as saying next week’s MSDF dispatch is in line with Prime Minister Shinzo Abe’s “free and open” Indo-Pacific strategy. The U.S. military’s Pacific Command has been renamed the Indo-Pacific Command to strengthen ties with Indian Ocean nations amid China’s growing military and economic clout in the region. The U.S. Navy has sent warships to the South China Sea as part of its “freedom of navigation” operations to challenge claims it says violate international law.

With its own dispatch, Tokyo is likely also aiming to respond to Beijing’s increasing assertiveness in the disputed waterway. Last year, Japan sent its Izumo helicopter destroyer to the South China Sea for a three-month tour in its biggest show of naval force in the region since World War II.

Washington and Tokyo have blasted Beijing for the island building, fearing the outposts could be used to restrict free movement in the waterway.

Malcolm Cook, a senior fellow at ISEAS-Yusof Ishak Institute in Singapore, said that while the upcoming dispatch of naval firepower was significant, it did not necessarily mean that Japan was “emboldened” to test China’s mettle.

“I do not think Japan is emboldened but rather increasingly worried about the regional security environment and is responding by trying to do more to address these worries,” he said.

Collin Koh, a specialist in regional naval affairs at Singapore’s S. Rajaratnam School of International Studies, said that “while the engagements might be modest compared to those customarily undertaken by the U.S. and other established external security partners … Japan’s slate of engagements appear to have been well received by regional governments.”

Koh said that Japan’s “activities don’t touch on politically and operationally sensitive areas, which helps to also further project the soft power aspect of this voyage.”

This, he said, is all the more significant considering that until recent years, Japan wasn’t at all considered an active player in defense and security engagements in South and Southeast Asia.

“Prior to this mission last year, MSDF and Japan Coast Guard presence was less regular — normally the MSDF port calls were undertaken as part of the task forces deployed to and from the counterpiracy and other allied operations in the Indian Ocean — more of the ‘along the way’ arrangements rather than specifically focused on building defense and security engagements.”

Now, through the 2016 Vientiane Vision — Japan’s guiding principle for defense cooperation with the Association of Southeast Asian Nations (ASEAN) — there’s not only a strategic policy direction to guide these activities, but also an overall political reason to remain engaged, Koh said.

“The MSDF long-duration mission to this region is therefore a manifestation of this, and a visibly tangible one at that,” he added.

That point — the visibility of the upcoming dispatch — is likely to anger China after a recent “milestone” agreement with ASEAN on a draft code of conduct that will lay the foundation for negotiations over the South China Sea. Beijing could use this agreement as reason to call on outside parties — such as Japan and the U.S. — to refrain from complicating the situation in the waterway, experts say.

Regardless, regional nations are expected to positively view deeper Japanese security involvement in the area, including the upcoming port calls and joint exercises.

“ASEAN countries especially would welcome such voyages, as part of their advocacy for an inclusive regional security architecture,” said Koh.

Information from AFP-JIJI added