Philippine plans to exit the Visiting Forces Agreement signed with the US in the 1990s won't go into effect until August, but the move is already raising concerns about relations to the US.The potential end of that deal, and a diminished US military presence, comes at a time when the US and its partners in the region are seeking to counter China's efforts to expand its influence.Visit Business Insider's homepage for more stories.Philippine President Rodrigo Duterte's recent decision to withdraw from the Visiting Forces Agreement comes after repeated threats to pull out, but his decision to ditch the pact now could undermine the ability of the US and its partners to counter China's ambitions in the region.The VFA, signed in 1998, gives legal status to US troops in the Philippines. Duterte, a longtime critic of ties to the US, gave formal notice of withdrawal to the US this month, triggering a 180-day period before the exit is finalized.Duterte believes the Philippines should be more militarily independent, a spokesman said, quoting the president as saying, "It's about time we rely on ourselves."The decision is "chiefly the product of Duterte's deep, decades-long anti-US sentiment," Prashanth Parameswaran, a senior editor at The Diplomat and a Southeast Asian security analyst, said in an email to Business Insider.Since taking office in 2016, Duterte has "found just about any excuse he can to make threats against the alliance, be it canceling exercises or separating from the United States," Parameswaran added.Duterte has spurned the US since he took office and bristled at US criticism of his human-rights record. Both the US and Duterte have high approval ratings among the Philippine public, however, while a large majority there have little or no confidence in China.Duterte has expressed affinity for President Donald Trump, but he still seeks closer relations with Beijing. Duterte has also been criticized at home as Chinese investments have been slow to arrive and as China acts assertively in the region, pursuing its claims in the South China Sea and drawing allies away from Taiwan."It's a competition. China's competing," Chad Sbragia, deputy assistant secretary of defense for China, said Thursday at a US-China Economic and Security Review Commission hearing on Capitol Hill."There's very clear recognition that China is putting pressure and using every tool within its disposal to try to draw those countries" away from cooperation with the US, Sbragia said. "That's a condition we're taking head on. That's very serious for us.""I don't doubt China will relish the deterioration in the US-Philippine alliance," Parameswaran said. "Beijing has long considered US alliances a relic of the Cold War and a manifestation of US efforts to contain its regional ambitions."'A US loss is China's gain'The US and the Philippines, which the US ruled as a colony during the first half of the 20th century, have a decades-long diplomatic and military relationship.That relationship and the benefit it offers the Philippine security establishment, as well as US popularity in the Philippines, are among the reasons why Manila may not follow through on withdrawal.Philippine officials have also hinted that the notice of withdrawal is a starting point for negotiations over the VFA, which some have said are needed "to address matters of sovereignty." Philippine politicians have also questioned Duterte's authority to exit the agreement.But the US shouldn't assume that Duterte is bluffing or looking for leverage, said Gregory Poling, director of the Asia Maritime Transparency Initiative at the Center for Strategic and International Studies."He has been anti-American his entire adult life and has been consistently saying he wants to sever the alliance and bring the Philippines into a strategic alignment with China," Poling said in an email."That said, six months is a long time in politics. If Duterte walks this back, it won't be because a plan to renegotiate with Washington plays out," Poling added, "it'll be because of internal pressure, possibly in response to whatever natural disaster, Chinese act of aggression, or terrorist act in Mindanao happens between now and then."The VFA allows US troops to operate on Philippine territory, including US Navy crews and Marine Corps units.Ending the agreement would jeopardize the roughly 300 joint exercises the two countries conduct every year, complicating everything from port calls to the Mutual Defense Treaty, which commits the US to the Philippines' defense in case of an attack. It would also be harder for the US to provide aid in response to natural disasters."It's basically [changing] the protocols of how you would work together if it actually goes through," Army Secretary Ryan McCarthy said this month.Many naval activities will be unaffected because they can be carried out without entering Philippine territory, Poling said."But large-scale land and air exercises will be impossible, as they were from 1990-1999," Poling added, referring to a period when Manila's failure to renew a mutual basing agreement led to the withdrawal of US forcesincluding the closure of Naval Base Subic Bay, the largest US base in the Pacific.Gen. Felimon Santos Jr., Philippine armed forces chief of staff, has said about half of all joint military engagements would be affected by the end the VFA, Poling noted.Philippine Defense Secretary Delfin Lorenzana has said joint exercises with the US would continue during the 180-day period, including the multinational Balikatan exercise that has taken place in the Philippines every spring for 35 years.Once termination is final, however, the Philippines would "cease to have exercises" with the US, Lorenzana said.Santos Jr. has downplayed the effects of withdrawal, saying it will make the Philippines "self-reliant" and that Manila would expand bilateral exercises it has with other in the region, including Australia and Japan.But there are legal and logistical limits on the military activities those countries can undertake with the Philippines, which has one of the weakest militaries in the Asia-Pacific.The erosion of the US-Philippine military relationship raises the prospect of Beijing making moves like those it made in the South China Sea in the 1990s, when it occupied Mischief Reeffirst with small wooden structures and then, a few months before the VFA went into force in 1999, with fort-like structures made of concrete.In the years since, China has expanded and reinforced its presence in the South China Sea, building military structures on man-made islands there. Mischief Reef is now Beijing's biggest outpost in the disputed waters."Beijing will work to make sure that a US loss is China's gain" and build on inroads made with Duterte, Parameswaran said."These gains may include those that are not in the security realm, such as tightening economic ties or helping Duterte deliver on some of his domestic political goals," Parameswaran added. "But they will nonetheless be consequential, because the broader objective is to move Duterte's Philippines closer to China and away from the United States."SEE ALSO:A major US ally in the Pacific wants to scrap an important military deal with the US, and that may give China an edgeJoin the conversation about this storyNOW WATCH: Here's why so many nations want to control the South China Sea ' and what China wants to do Click here to read full news..