U.S. Weighs Options, on Air and Sea WASHINGTON â€” American military planners are sifting through a range of options as the United States, like other Western nations, weighs the response to the bloody Libyan military assaults on rebels trying to oust Col. Muammar el-Qaddafi. Rebel commanders have begged for American strikes on troops and weapons that have turned on civilians and assaulted strongholds of the resistance. And on Sunday, three influential members of the United States Senate, from both parties, renewed the call for a no-flight zone to ground the Libyan Air Force and prevent it from attacking its people. They also pressed the Obama administration for a more aggressive response, including supplying intelligence, arms and training to the rebels. The defense secretary, Robert M. Gates, and top commanders have warned of political fallout if America again attacks a Muslim nation, even to support a popular revolt. So military planners on the Pentagonâ€™s Joint Staff and in its field commands are offering a broad range of approaches, depending on how events play out in Libya and how tough the United States and its allies want to be. Even without firing a shot, a relatively passive operation using signal-jamming aircraft in international airspace could muddle Libyan government communications with military units. Administration officials said Sunday that preparations for such an operation were under way. The latest military force to draw within striking distance of the Libyan capital, Tripoli, is the 26th Marine Expeditionary Unit aboard two amphibious assault ships, the Kearsarge and the Ponce. The unit provides a complete air, sea and land force that can project its power quickly and across hundreds of miles, either from flat-decked ships in the Mediterranean Sea or onto a small beachhead on land. In this task force are Harrier jump-jet warplanes, which not only can bomb, strafe and engage in dogfights, but can also carry surveillance pods for monitoring military action on the ground in Libya; attack helicopters; transport aircraft â€” both cargo helicopters and the fast, long-range Osprey, whose rotors let it lift straight up, then tilt forward like propellers to ferry Marines, doctors, refugees or supplies across the desert â€” landing craft that can cross the surf anywhere along Libyaâ€™s long coastline; and about 400 ground combat troops of the 1st Battalion, 2nd Marines. Not that every option would require such firepower. Helicopters from that same Marine Expeditionary Unit, for example, were sent to assist after the catastrophic floods in Pakistan. Pentagon planners can also look at templates from large humanitarian missions carried out after the Haitian earthquake, Pakistani floods and an Indonesian tsunami, as well as the military operation to protect and feed residents of Iraqi Kurdistan after the first Persian Gulf war. And the Kearsarge provides a large floating hospital. Already, a military airlift of refugees is under way. Four more flights of propeller-driven C-130s carrying international refugees back to their home nations were planned for Sunday. Earlier military flights carried relief supplies for refugee camps just beyond Libyaâ€™s border and then carried out Egyptians who had escaped into Tunisia. But the firepower arriving off Tripoli could prove convenient, and not only to protect the expedition from coming under attack. The flotilla can be seen as a modern-day example of â€œgunboat diplomacyâ€ â€” intended to embolden rebels and shake the confidence of loyalist forces and mercenaries, perhaps even inspiring a palace coup. Should Mr. Obama opt for direct intervention, he has a range of choices short of what Mr. Gates cautioned could be an expensive, exhausting â€œno-flightâ€ zone â€” though that might be simpler than he portrayed, if the United States proved willing to attack Libyan runways, missiles and radars outright. Another tactic would be to air-drop weapons and supplies to rebels, an idea floated Sunday by Stephen Hadley, who served President George W. Bush as national security adviser. â€œIf there is a way to get weapons into the hands of the rebels, if we can get antiaircraft systems so that they can enforce a no-fly zone over their own territory, that would be helpful,â€ Mr. Hadley said on â€œState of the Unionâ€ on CNN. Other options include inserting small Special Operations teams, perhaps just a dozen soldiers, to assist the rebels, as was done in Afghanistan to topple the Taliban. The teams are specially trained to turn ragtag rebel groups almost overnight into more effective fighters, with a modest infusion of know-how, equipment and leadership. A handful of strikes on valued government or military targets could be ordered, as was done in the Gulf of Sidra raids in 1986 after Libya was linked to the bombing of a Berlin club popular with American troops. (An American plane was shot down, and residential areas were blasted, showing the many risks of even a limited operation.) There are ample planes based in Europe and on the aircraft carrier Enterprise and its strike group, now in the Red Sea, for missions over Libya. Pentagon officials said Sunday that those vessels were carefully sailing in the direction of the Suez Canal, gateway to the Mediterranean. Support for a no-flight zone was voiced Sunday by Senator John Kerry, the Massachusetts Democrat who chairs the Senate Foreign Relations Committee, as well as two Republicans â€” Senator Mitch McConnell of Kentucky, the minority leader, and Senator John McCain of Arizona. Mr. McConnell urged exploring other options like â€œaiding and arming the insurgents.â€ But he cautioned he was â€œnot sure who the insurgents areâ€ so the United States â€œought to make sure who weâ€™re dealing with here.â€ But the administration offered no change in its position. â€œLots of people throw around phrases like no-fly zone â€” they talk about it as though itâ€™s just a video game,â€ William M. Daley, the new White House chief of staff, said in at appearance on â€œMeet the Pressâ€ on NBC. Gen. John P. Jumper, who served as Air Force chief of staff from 2001 to 2005 and commanded all Air Force missions in the Middle East from 1994 to 1996, said past flight-denial missions over Iraq proved that requirements reach far beyond the jet fighters and bombers that are the most obvious instruments of carrying out a presidential order. The destruction of Libyan air-defense radars and missile batteries would be required, perhaps using missiles launched from submarines or warships. A vast fleet of tankers would be needed to refuel warplanes. Search-and-rescue teams trained in land and sea operations would be on hand in case a plane went down. The fleet of aircraft needed for such a mission would easily reach into the hundreds. Given the size of such a mission, it would be expected that American and NATO bases in Europe would be used, and that an American aircraft carrier would be positioned off Libya.