The symbolism Tuesday was appropriate for a nation at war: A somber president in a plain blue suit describing military strikes in Syria the night before, an American flag fixed in his lapel while a Marine Corps helicopter waited behind him.

President Obama's message was dry as bone: The United States has gone into battle again, in yet another Muslim country, to attack the menace of violent extremism. This time, at least, the president could announce that U.S. military action against Muslim targets was joined by a coalition of leading Arab nations: Saudi Arabia, the United Arab Emirates, Jordan, Bahrain and Qatar.

Obama's war strategy is still a work in progress. But some basic outlines are emerging in conversations with senior U.S. officials. The president has avoided a full congressional debate on the strategy, but here's a glimpse of what the White House is planning.

The president insists that there won't be American combat "boots on the ground," but the role of American military advisers assisting Iraqi and perhaps rebel Syrian forces will be crucial. How far forward they will go into battle, to coordinate operations and call in air support, is still being debated.

Obama and his advisers, led by his special envoy, Gen. John Allen, have focused on five main lines of operation against the Islamic State: direct military action; counterterrorism operations against foreign fighters; disruption of financing; humanitarian assistance; and media activities to "de-legitimize" the extremists.

Military action is the centerpiece. The United States will lead air attacks on the Islamic State and other terrorist groups in Iraq and Syria. Perhaps more important, it will train and assist Iraqi forces and the amorphous Syrian "moderate opposition." Obama wants most of the trainers to be overt, uniformed U.S. military personnel, operating under standard Title 10 legal procedures, rather than troops detailed to the CIA under Title 50 "covert action" authority. The White House believes the coalition will work better under these more transparent rules.

The Iraqis to be trained will include members of the existing military that collapsed so ignominiously in Mosul. The United States will also lead the training of about 10,000 Sunni "national guard" troops, drawn from tribal fighters. These Sunni forces will act as a local gendarmerie, to keep order in their home regions once Islamic State fighters have been cleared. Training camps are already under construction in Jordan and northern Iraq, and are expected to be ready in three to six months.

The U.S. military will also lead the training of Syrian forces, but this will take longer because the opposition there starts from a low base of readiness. The hope is that by sometime next year, a well-vetted force of at least 5,000 Syrians, trained in Saudi Arabia and other countries, will be ready. It will move into areas in southern and northern Syria where the Islamic State and al-Qaida affiliates are now dominant. The big Syrian ground battles may be a year away.

Obama has tapped Maj. Gen. Michael Nagata to head the training mission. He's an Army special forces officer with many sensitive combat assignments, as well as a stint commanding U.S. military activities in Islamabad, Pakistan. Like Allen, a retired Marine who helped oversee the "Sunni Awakening" in Iraq, Nagata has experience in tribal cultures such as those where U.S. trainers will be operating.

The terrorism threat against the United States and Europe comes from the "foreign fighters" who have joined the Islamic State and al-Qaida. The U.S. will combat these recruits by discouraging them from going to Syria and Iraq, monitoring and attacking them while there, and stopping them from committing terrorist acts when they leave.

One interesting puzzle is what to do about foreign fighters who become scattered after punishing U.S.-led attacks. These tribeless jihadists will be on the run, pursued by government forces in Iraq and Syria and by local tribal fighters.

The struggle to de-legitimize the extremists, through the media and elsewhere, will depend on Muslim nations that have sometimes been wary of earlier counterterror efforts against al-Qaida. A useful coordinator should be the Global Counterterrorism Forum, co-chaired by the United States and Turkey, which met Tuesday in New York.

Perhaps the trickiest part of the campaign is how to implement its phases. The United States is likely to strike field commanders whenever possible. But simply decapitating the leadership could create a chaotic battlefield that would remain unstable for years to come. Obama said Tuesday that "the overall effort will take time" - which surely means beyond the end of his presidency.