MANILA, Philippines - American troops, warships and aircraft can once again use their former naval and air facilities in Subic, Zambales and in Clark Field in Pampanga as long as they have prior clearance from the Philippine government, a senior defense official said.  " They can come here provided they have prior coordination from the government," Defense Undersecretary for defense affairs Honorio Azcueta told reporters after his meeting with Gen. Martin Dempsey, chairman of the US Joint Chiefs of Staff, on Monday.