Washington, Feb 28: The United States warned Americans still in Haiti to seek ''safe haven'' because the security situation had deteriorated significantly and safe travel out of the country by regularly scheduled commercial means was no longer possible. Since an armed revolt against President Jean-Bertrand Aristide exploded on Feb 5 in the poorest nation in the western hemisphere, rebels have taken over key cities, lawlessness has spread and foreigners and Haitians have fled the country. ''The security situation in Haiti has deteriorated significantly and safe travel out of the country by regularly scheduled commercial means is not possible at this time,'' the state department said. ''US citizens who remain in Haiti should seek a safe haven and remain there until the situation improves or safe transport out of the country becomes available,'' it said. All major commercial air carriers have suspended operations in and out of Haiti and the border with the neighboring Dominican Republican is sometimes closed. It also said the Haitian government has ''failed to maintain order'' in Port-Au-Prince and other cities and in some instances has assisted in violently repressing demonstrations. Six days ago, the United States ordered nonessential US Embassy staff and family members to leave Haiti. Earlier yesterday, defense officials said the US government is considering sending three warships with about 2,000 US Marines, headed by the helicopter carrier USS Saipan, to rebellion-torn Haiti as the pentagon weighs options to address the crisis. Defense officials identified a range of options being explored. One possibility was to send the three ships and marines to the Haitian Coast, and then put marines on the ground in Haiti to protect Americans and US facilities, or potentially to serve as a peacekeeping force depending on political developments, officials said. Officials said far fewer than 2,000 marines, if any might be put ashore. Another option was to send ships without large numbers of Marines merely for maritime interdiction or to support US Coast Guard ships trying to prevent a mass exodus of Haitian refugees to the United States, officials said. Another option was to take no further military action, officials added. Bureau Report