Villar, chairman of the Senate committee on foreign relations, said he would insist on the ratification of the MLSA should the Senate later reclassify the military agreement as a treaty.
He said it was the constitutional duty of the Senate to look into international agreements entered into by the government.
"We will look into the allegations that the MLSA contains provisions that are not only for the purpose of implementing existing agreements, but require changes in national policy," he said.
Villar said he would like to know in particular the benefits the Philippines will gain from signing the agreement with the United States. "We cannot compromise the future of our country with a hasty decision," he said.
Villar filed the resolution calling for a joint hearing by the committee on foreign relations and national defense, chaired by Sen. Ramon Magsaysay Jr.
He said the hearing may be preferably conducted tomorrow if Foreign Secretary Blas Ople and Defense Secretary Angelo Reyes are both available.
Villar said both Ople and Reyes should explain before the joint committee why they insisted on classifying the MLSA as "a low level executive agreemen" instead of a treaty which would have needed Senate concurrence.
Senate President Franklin Drilon said senators are still in the dark on the MLSA and the appearance of Reyes and Ople before the joint Senate hearing could help clarify issues.
Magsaysay was the only senator at the hastily called Senate briefing conducted by Reyes and Ople, hours after the signing of the agreement at Camp Aguinaldo last Thursday.
"We will decide on the basis of these briefings if indeed this is a treaty which requires Senate ratification, or a mere executive agreement as alleged," Drilon said.
Drilon stressed that what is important is not the nomenclature given by Reyes to the MLSA but the substance. "The substance, not the form, will determine whether or not a ratification of the MLSA is necessary," he said.
Villar said the signing of the agreement surprised many groups which made them even more doubtful on the motive of the administration.
He stressed the position of the Senate that prior consultations should have been made by Malacañang before the final draft of the agreement was signed.
"This would have prevented the public from doubting the intentions of the government," Villar stressed.
Malacañang has claimed the signing of the agreement is no big deal for the Senate to look into since it will not compromise the sovereignty and security of the country.
Reyes defended the MLSA since it would boost the anti-terrorism campaign of the Armed Forces of the Philippines.
Ople went on to challenge critics to question the legality of the MLSA before the Supreme Court or a public debate on the issue.
Yesterday, Bayan Muna party-list Rep. Crispin Beltran took up the challenge and said he is willing to debate with Ople on the MLSA.
"Ople is far from the grand statement that he probably thinks he is," said the militant legislator.
"(He) has pluck to say that the Supreme Court will immediately throw out any complaints against MLSA, as if he already knows how the SC justices think," he said.
Beltran argued that the MLSA is not defensible by any standards, whether legal or moral, adding that the Arroyo administration can present all arguments it wants but will never be able to defend the agreement as beneficial for the country.
But Malacañang twitted its critics for raising the issue of sovereignty as argument in the call for rejecting MLSA.
Press Secretary Ignacio Bunye said there is no basis for those against MLSA to claim it violated the countrys sovereignty, insisting the military agreement has basically the same format as similar documents negotiated by the US with 56 countries.
Bunye claimed the MLSA "template agreement" of the Philippines with the US was a unique version since this was enhanced by the suggestions made by Vice President Teofisto Guingona when he was still foreign affairs secretary.
Aside from the basing rights issue, Bunye also credited as inputs of Guingona the specific provisions of the MLSA about facilities which should be at the control of the host country at all times, the period of the agreement shortened to five years and the review procedures of the pre-termination of the agreement.
"So all of these kinds of provisions were really put in the final agreement," Bunye stressed.
The Department of Foreign Affairs (DFA) has prepared a legal primer to address the questions posed by Guingona on the pact, in anticipation of a case against the MLSA before the Supreme Court.
"We have already anticipated that opposing groups will take the case to the Supreme Court. That is why we have prepared this primer to address their concerns and apprehensions on the MLSA," a ranking DFA official said.
Critics of the Visiting Forces Agreement, an equally controversial defense pact with the US ratified by the Philippine Senate in 1999, also went to the Supreme Court to challenge the VFAs constitutionality, but they were rebuffed by the high tribunal.
According to Bishop Tomas Millamena of the Iglesia Filipinas Independiente (IFI), the MLSA can serve as a legitimate license for the armed intrusion of the United States in the counter-insurgency operation of the Armed Forces of the Philippines (AFP).
Millamena said this could be done within the framework of the US "war on terror."
He pointed out that the MLSA will further violate the countrys sovereignty and territorial integrity with the presence of the US military which could also aggravate the three-decades long armed conflict with the communist rebels.
Militant groups based in Central Luzon also stepped up their opposition against MLSA by claiming the military logistics agreement would eventually drag the country into the war against Iraq.
During their protest rally in Clark Field in Pampanga, the groups Bagong Alyansang Makabayan (Bayan) and the Kilusan para sa Pambansang Demokratiko (KPD) expressed their fears that the former military airbase might be used by US forces in their war against Iraq.
"We run the risk of repeating what happened during World War II where Japan invaded the Philippines because of US military presence here," Bayan-Central Luzon chairman Roman Polintan said in describing MLSA as an "act of treason."
KPD secretary-general Millet Morante said "(the agreement) is downright alarming and utterly deplorable."
In Metro Manila, Kilusang Mayo Uno (KMU) secretary-general Elmer Labog said they will launch a nationwide protest action against the signing of the MLSA on Nov. 30, Bonifacio Day.
Labog said MLSA will eventually lead to the return of US bases and indefinite stay of American military forces in the country. - With reports from Marichu Villanueva, Aurea Calica, Sandy Araneta, Romel Bagares, Mayen Jaymalin, Ding Cervantes