FORT MAGSAYSAY, Philippines (REUTERS) - Philippine soldiers crawl through narrow pipes to save civilians and haul casualties by ropes from atop a derelict building, coached by US army teams in a simulation of a rescue after a ferocious typhoon.

Soldiers practice putting on protective overalls and drilling through collapsed rubble, in exercises part and parcel of "Balikatan" (shoulder to shoulder), the conventional warfare exercises that for decades have bolstered a treaty alliance and helped preserve a US strategic foothold in Asia.

But this year's edition is a shadow of what it was a year ago, involving only half the 11,000 troops, and stripped of all combat-related exercises at the behest of Philippine President Rodrigo Duterte.

Duterte makes no secret of his disdain for an alliance with the United States that he sees as an obstacle to his rapprochement with China, and has tamed Balikatan to avoid provoking Beijing, and to hammer home his message that the Philippines is no US lackey.

The 2016 exercises, which Duterte had said would be "the last", featured live-fire drills, amphibious landings and a combat simulation of the re-taking of a South China Sea island from an unspecified enemy.

What's left this year is largely Humanitarian Assistance and Disaster Response (HADR) training, seen on Friday at a military base in Nueva Ecija province, where forces practised for the scenario of a typhoon striking the capital Manila.

"It's instruction-based, hands-on and practical and they're doing pretty good," said Sergeant First-class Jay Bal, a Filipino-American who is among 30 members of the Hawaii National Guard training Philippine army engineers and rescue teams.

The idea of Balikatan was to rehearse a joint defence plan under the old allies' 1951 Mutual Defence Treaty, one of several agreements Duterte has threatened to abrogate, arguing the US troop presence could make the Philippines a target for Chinese aggression.

Duterte, who holds talks in Beijing with Chinese President Xi Jinping on Monday, has reversed a Philippine foreign policy that prized close US ties and saw China's assertiveness in the South China Sea as a threat to its sovereignty.

Duterte has denounced Washington for "hypocrisy" and for treating the Philippines "like a dog". He has shunned all US activities in the Philippines, but made a point of touring visiting warships from China and Russia in recent weeks.

AVOIDING ANTAGONISM

Defence Secretary Delfin Lorenzana said the training exercises were valuable but Duterte wanted no more "war games".

"We are concentrating on HADR, counter-terrorism, and many things related to that," he said last week. "The president doesn't want to antagonise some people in the neighbourhood."

Like many US officials, Marine Lieutenant-General Lawrence Nicholson, the commander leading Balikatan, insists the alliance remains strong, and the removal of combat training did not devalue the exercises. "These are skills that are pertinent to any type of military operation," he said.

Many experts say that geopolitical realities mean ties are unlikely to take a permanent hit from Duterte's hostility and say the Philippine military's mistrust of China means it will not risk losing its US support.

Richard Heydarian, an expert on politics and international affairs at Manila's De La Salle University, said the bare-bones Balikatan indicated a "mitigated downgrade" in the US relationship, but that was easily reversible and contingent on China's actions and the foreign policy approach of the Trump administration.

"Duterte clearly respects his military, which is clear about its suspicions of China but unclear about America," he said, referring to the uncertainty about US priorities in the region.

"China is consolidating with its strategic objectives, but I don't think China will forget those plans just because Duterte talks nice to them."