Senga replaced Gen. Efren Abu, who has retired. At yesterdays formal turnover of command at Camp Aguinaldo in Quezon City, the President ordered Senga to keep the military out of partisan politics.
Senga enjoined the military to ensure that "every Filipino soldier must be a symbol of peace."
"Our entire organization must be insulated from politics. We shall remain apolitical, focused on our primary mandate as protector of the people and our countrys sovereignty," he said in a speech.
Maj. Gen. Hermogenes Esperon, head of the Special Operations Command, will formally take over Sengas previous post as Army chief tomorrow, officials said.
Senga who as a battalion and brigade commander led operations against communist and Muslim rebels urged soldiers to focus on their task of maintaining peace.
"The AFPs transformation at this point is not so much the modernization of equipment and arms to match those of more advanced countries. We cannot afford it anyway," Senga said. "The transformation that we need today is in changing the way we, soldiers and leaders, think about the challenges and opportunities presented to us by the program for reform."
In a speech at the ceremony, Mrs. Arroyo thanked the military for "successfully guarding our democracy, especially these past few months."
"General Senga, I expect you to keep the Armed Forces of the Philippines within the Constitution and not to allow any partisan quarters to undermine the chain of command," Mrs. Arroyo ordered.
"I expect you to further reform and professionalize the chain of command as your predecessors have initiated this effort."
Senga vowed to carry on the reforms begun by Abu, including streamlining the 115,000-strong military, fighting corruption and maintaining neutrality in the political crisis besetting Mrs. Arroyos presidency.
Mrs. Arroyo also ordered Senga not to let up on the governments campaign against terrorism and "finish off the terrorists wanting to squander the peace process."
"We face not only domestic controversies but also an oil crisis of global proportions, compounded by a global resurgence of terrorism," Mrs. Arroyo said. "You are forced, through your role as soldiers of the Philippines, in a battle against terrorism."
Beyond battling Muslim rebels and foreign militants from the al-Qaeda-linked regional network Jemaah Islamiyah, troops are fighting communist guerrillas who are active in most parts of the largely Roman Catholic country.
The government is in the midst of Malaysian-brokered peace talks with the Moro Islamic Liberation Front, to try to end a three-decade-long conflict that has killed 120,000 people and stunted development in Mindanao.
Abu reached the mandatory retirement age of 56 in June, but Mrs. Arroyo extended his term "to ensure the smooth transition of military leadership," her spokesman Ignacio Bunye said.
Senga will serve less than one year, until he retires at the mandatory age of 56 in July next year.
A stable and neutral military is seen as crucial for Mrs. Arroyo to maintain her hold on power.
Mrs. Arroyo faces an impeachment trial over accusations that she rigged last years election and following allegations that her family pocketed illegal gambling payoffs. The charges have set off fresh coup rumors and her most serious political challenge.
Allegations against her, based on wiretapped phone calls, suggest generals may have helped her cheat in last years presidential election, sparking anger among middle- to lower-ranking officers.
Mrs. Arroyo earlier fended off two coup attempts a bloody attempt by supporters of ousted President Joseph Estrada to storm Malacañang in May 2001, and a brief military takeover of an upscale shopping mall and apartment complex two years ago.
Before becoming army chief, Senga served as AFP deputy chief of staff for operations, deputy chief of staff for intelligence and commander of the armys counter-terrorism group. He also served as military spokesman under Estrada.
A 1972 graduate of the Philippine Military Academy, Senga underwent training at the US Army Infantry School at Fort Bragg in California, the US Defense Intelligence College and the US Pacific Command, as well as in the United Kingdom and Israel.
He has a masters degree in business administration and completed two years of law school.
The Philippines is a staunch ally of Washington in the war on terror but its armed forces are poorly equipped, undermined by corruption and riven with discontent that has spawned more than a dozen attempted coups in the last two decades.
Senior commanders recently sought to calm fears of another intervention by vowing to stay neutral in the political crisis. But analysts say there is still considerable restiveness in the ranks over low pay and the pace of reforms.
Critics accuse Arroyo of using "revolving door" appointments of military chiefs to ensure their loyalty with better pay, pensions and title of office.
Meanwhile, Sen. Alfredo Lim called on Senga yesterday to reopen a case involving a Philippine Navy ensign who was believed to have been murdered aboard a navy ship in 1995.
In September 1995, the body of Ensign Philip Andrew Pestaño was found aboard the BRP Bacolod City. Investigators said he may have committed suicide but a bullet wound in the head indicated that he may had been murdered.
"We are asking Defense Secretary Avelino Cruz and incoming AFP chief Senga to reopen the case, to find those responsible and those accessory to the crime," said Lim, a former Manila police chief.
Lim hopes that Senga would grant an appeal by Pestaños relatives to reopen the case. It was believed that Pestaño was silenced by drug smugglers. With reports from AP, Cecille Suerte Felipe, Evelyn Macairan