PLO chairman Yasser Arafat has asked the U.S. to intercede in the deadlockedMideast peace talkswith Israel, hoping the outside help will pressure Israel into extending Palestinian autonomy. Arafat made the appeal after Israeli Prime Minister Yitzhak Rabin refused Thursday to withdraw troops from the Palestinian territory, or to go forward with the Mideast peace accord as long as Islamic militants continue to attack Israelis. Arafat, who received a private phone call from the State Department today, also asked Russia, Egypt, Norway and the United Nations for help. "The situation is very sensitive and critical and very dangerous as well," a PLO spokesman said today. "Unless there is advancement in the peace process, things could be uncontrollable." Israeli officials balked at mediation.