Russia says 'tragic mistake' to assign blame too soon for Syrian gas attack MOSCOW (Reuters) - Russia said on Sunday that assigning blame too soon over the alleged chemical weapons attack in Syria would be a "tragic mistake," before a U.N. investigation on Monday. Without directly naming the United States but in comments that warned against any military action against Syrian President Bashar al-Assad's government, Moscow urged against "hurried conclusions" over the reports of a poison gas attack. "We strongly urge those who, in trying to impose their opinion on U.N. experts ahead of the results of an investigation, announce the possibility of military action against Syria, to exercise discretion and not make tragic mistakes," the Russian Foreign Ministry said in a statement. U.S. President Barack Obama met his military and national security advisers on Saturday to debate options, and U.S. naval forces have been repositioned in the Mediterranean to give Washington the option of an armed strike. Russia, which has suggested that Syrian rebels may have carried out the attack, said it welcomed Syria's decision to allow U.N. experts to visit the site where many hundreds of people were reported dead on Wednesday. Secretary-General Ban Ki-moon's office said in a statement on Sunday that Syria had promised to observe a ceasefire at the site in the suburbs of Damascus while a U.N. team begins "on-site fact-finding activities." Reporting by Alissa de Carbonnel; Editing by Louise Ireland and Pravin Char