The US defence secretary, Pete Hegseth, has met with the Philippine president, Ferdinand Marcos, in Manila saying the two countries must stand “shoulder to shoulder” in the face of the threat represented by China.

Hegseth’s meeting at the presidential palace comes as he opens a tour of Pacific allies that risks being overshadowed by a mounting scandal over leaked plans for military strikes.

“Deterrence is necessary around the world but specifically in this region, in your country, considering the threats from the Communist Chinese,” he said.

Hegseth’s Manila visit, to be followed by trips to Tokyo and second world war battleground Iwo Jima, follows months of confrontations between Philippine and Chinese vessels in the disputed South China Sea.

Beijing claims almost the entirety of the crucial waterway despite an international ruling that its assertion has no merit.

“Friends need to stand shoulder to shoulder to deter conflict to ensure that there’s free navigation, whether you call it the South China Sea or the West Philippine Sea,” Hegseth said.

“Peace through strength is a very real thing.”

The trip – aimed at bolstering ties in the Asia-Pacific region amid rising tensions with Beijing – comes as Hegseth faces calls to resign by Democratic lawmakers and a Republican congressman’s push for an independent report.

The US defence chief revealed details of strikes on Iran-backed Houthi rebels in Yemen in a group of top administration officials on the messaging platform Signal, according to a senior journalist added to the chat by accident.

Hegseth is expected to meet his Philippine counterpart, Gilberto Teodoro, on Friday.

In response to China’s growing influence, the US has been strengthening alliances with countries in the Asia-Pacific region, including the Philippines.

Manila and Washington have deepened their defence cooperation since Marcos took office in 2022 and began pushing back on Beijing’s sweeping South China Sea claims.

In recent years, top US officials have warned that an “armed attack” against the Philippines in the waterway would invoke the two countries’ mutual defence treaty. They have expanded the sharing of military intelligence and boosted to nine the number of bases US troops have access to on the archipelago.

Given the Philippines’ proximity to Taiwan and its surrounding waters, Manila’s cooperation would be crucial in the event of a conflict with China.

Hegseth’s visit overlaps with bilateral military exercises that will expand in April to include the countries’ navies and air forces.

Despite mounting pressure over the Signal leak, Donald Trump has defended Hegseth. “Hegseth is doing a great job, he had nothing to do with this,” said the US president when asked by AFP whether the defence secretary should be considering his position.

He also repeated his insistence that no classified information was shared in the breach, adding that national security adviser Mike Waltz “took responsibility” for the error.

Waltz added Goldberg to the group chat that included Hegseth, the vice-president, JD Vance, the national intelligence director, Tulsi Gabbard, and others.