US President George W. Bush has swept into the Philippines for an eight-hour visit to talk security and trade, celebrating a century of close ties against a backdrop of protests and potential terror attacks.
Bush, on a six-nation Asian tour built round a regional summit in Thailand, is expected to reiterate pledges of more military aid for Manila and investment in the south to help seal a peace deal with the nation's largest Muslim rebel group.
Bush and Arroyo shook hands as they met at the Malacanang presidential palace.
In a nation where a third of the 82 million people survive on a couple of dollars a day, some were outraged by the "fiesta" mood of a state-sponsored dinner before Bush departs for Thailand.
Thousands of demonstrators marched with banners denouncing the US leader as a bomb-cuddling warmonger and enemy of poor farmers. One effigy portrayed Bush as the grim reaper holding Arroyo like an infant with a US flag round her neck.
"This is a question of patriotism by the Philippine people against US imperialism," said Crispin Beltran, a congressman leading one group of protesters.
The marchers were met by police in riot gear backed by water cannon and tear gas, but there were no signs of violence.
With the al Qaeda-linked Abu Sayyaf and communist rebels vowing to disrupt the visit, the elite US and Philippine teams guarding the two presidents were in place more discreetly.
The Philippines is bound to the United States by a 48-year colonial past, Manila's fervent anti-communism during the Cold War and trade with its biggest export market.
For Arroyo, Bush's visit may translate into a much-needed shot in the arm as she seeks a fresh term in next May's election with the economy growing only sluggishly, state debt mounting and uncertainty still rumbling after a failed coup in July.