President Obama addressed the attacks in San Bernardino, Calif., and laid out his plan to destroy the Islamic State during his address from the Oval Office. (Associated Press)

To its critics, President Obama’s strategy to combat the Islamic State in Syria and Iraq is weak and incoherent. Even some of the staunchest U.S. allies and partners in the fight worry that the time for what they see as the administration’s incremental approach has long since passed.

The White House maintains that its strategy is comprehensive and that it’s working. Sharp increases in airstrikes and Obama’s recent decision to deploy Special Operations troops, officials say, are part of a fundamental change in the military’s mission developed this fall, along with a new diplomatic push to end the distraction of Syria’s civil war.

In his Sunday-night address to the nation following last week’s San Bernardino, Calif., shooting, Obama outlined the elements of the strategy, assuring Americans that there is a viable plan underway to decimate the Islamic State where it lives. “We will destroy ISIL and any other organization that tries to harm us,” he said, using an alternative name for the militants.

But the White House is clearly frustrated by its failure to communicate the elements of that plan and what it believes has been accomplished.

“Yes, there is a strategy,” Secretary of State John F. Kerry snapped in a speech Saturday. “I know the criticism. We all hear them. . . . But that doesn’t mean it’s wisdom.”

The administration’s insistence that its prudence and patience will pay off — vs. charges of too little, too late — have been the two opposing narratives of the 18-month battle against the Islamic State and the four-year Syrian war it has now overshadowed.

An examination of the recent course of events on the military and diplomatic fronts and interviews with a broad range of stakeholders and experts provide fuel for both arguments.

For more than a year after the Islamic State blitzkrieg swept across Syria and through Iraq to the Baghdad suburbs in the early summer of 2014, U.S. military operations, including airstrikes and training of local ground troops, were in what a coalition spokesman, Col. Steve Warren, called “crisis mode, just trying to keep the barbarians off the gate.”

The Iraqi army had fallen apart. In Syria, as civil war raged in the west, the militants consolidated their control over the north-central and eastern areas of the country, with virtually free access to Syria’s border with Turkey to infiltrate tens of thousands of foreign fighters and equipment.

Airstrikes begun by the United States and its coalition partners — Europeans in Iraq and Arab states in Syria — were tactical, focused on targets of opportunity and the need to prevent collapse. While domestic critics and allies in the region called for more strikes, more support for Syrian rebels, more U.S. boots on the ground and no-fly zones, the administration demurred.

In a broad assessment in August, the Pentagon determined it had succeeded in its initial goals of stopping further Islamic State expansion and reestablishing the foundations of a viable Iraqi military. Amid repeated failures in Syria to organize and arm a rebel force to fight against the militants in Syria, it found hope in the establishment of a Syrian Kurdish and Arab force that has driven the militants from much of the Turkish border.

Adoption of what the military says is its first real operational strategy, following the chaos of the initial year, was marked by September’s change of command of the Baghdad-based headquarters of the U.S.-led coalition against the Islamic State. “You have done what was necessary,” U.S. Central Command Gen. Lloyd J. Austin III told departing Lt. Gen. James L. Terry.

The new commander, Lt. Gen. Sean MacFarland, was charged with “operationalizing” the mission, Warren said.

“We always wanted to get into a position where we could apply multiple points of pressure at once, across the whole battle space,” said a senior administration official. “We’re now in position to actually do it. It’s not going to be perfect, it’s not going to be linear, it’s going to be extremely hard.”

Military and administration officials, most speaking on the condition of anonymity about internal decision-making, listed the elements of the comprehensive offensive against “core ISIL” on the ground in both Syria and Iraq.

In Iraq, the focus has been on cutting Islamic State supply lines into Mosul, the militant bastion in the northwest, in preparation for an eventual ground assault, and applying simultaneous pressure along militant front lines stretching south to the city of Ramadi, 70 miles west of Baghdad. “These are not blitzkrieg gains,” Warren said, “but painstaking, incremental work against a dug-in enemy” now made more effective with the ability to integrate airstrikes with a more organized and robust ground force.

Obama has authorized a new, Iraq-based Special Operations task force to conduct ground raids against Islamic State leadership targets in both Iraq and Syria. Administration officials have described a snowballing cycle in which more raids will take more leaders off the battlefield and provide more intelligence to plan still more raids. But it is unclear when the force, initially to number about 100, will be deployed.

Syria, with its separate wars against the Islamic State and between forces of President Bashar al-Assad and rebels seeking to unseat him, is far more complicated.

Regional allies such as Saudi Arabia, the United Arab Emirates and Jordan, who once flew strike missions along with U.S. warplanes, have largely dropped out, an absence the United States hopes to make up with new agreements with France and Britain.

The “whole battle space” concept includes simultaneous airstrikes along the eastern border with Iraq to further cut militant supply lines, on Islamic State-controlled oil fields, and in the north-central area, where Syrian Kurdish and Arab forces who have captured a wide swath of territory along the border from the militants are organizing to attack the de facto militant capital of Raqqa.

Obama has authorized the deployment of 50 Special Operations troops, the first official U.S. boots on the ground in Syria, to join those forces to assess their readiness and help develop tactical plans, although the Americans are not expected to arrive for several months, defense officials said.

In southern Syria, anti-Assad rebels have met with significant success against government forces, but the Islamic State, sensing an opening, has begun moving into the area. The United States is sending more money and equipment, including heavy, long-range artillery, to Jordan, both to protect its own border and to engage militant targets inside Syria.

But given the new threat to the homeland, the administration’s claims of incremental success have left scornful critics asking why it does not do more. Asked on NBC’s “Meet the Press” on Sunday what he hoped to hear in Obama’s speech, presidential hopeful Sen. Lindsey O. Graham (R-S.C.) replied: “That he’s going to change his strategy and come up with a regional army to go in destroy the caliphate in Raqqa. . . . The president doesn’t have a strategy.”

Mutual frustration has also been ongoing between the United States, as coalition leader, and regional allies, with some calling for a more aggressive U.S. policy. The United Arab Emirates said last week that it was willing to send ground forces into Syria — something Obama has consistently refused — if others would do the same as part of an international force.

But the region’s governments, including Turkey, are also deeply divided among themselves, leaving the administration as both whipping boy for their complaints and mediator for their disagreements as it tries to implement a broad strategy. In recent weeks, as Kerry has launched a diplomatic effort to bring the civil war to an end in order to shift attention to the counterterrorism fight, Obama himself has intervened in a series of conversations with regional leaders, including Turkish President Recep Tayyip Erdogan and Saudi King Salman.

Nowhere is the dissention more acute than in northwest Syria, where rebel groups separately backed by the United States and Europe, the Persian Gulf Arab states and Turkey are locked in a melange of battles, often beside forces of al-Qaeda affiliate Jabhat al-Nusra, against Assad’s military.

The entry of Russian warplanes and Iranian troops on Assad’s side in western Syria has further complicated the situation, increasing the conundrum of how to take back the nearby, remaining 60-mile strip of the Syria-Turkey border in Islamic State hands.

The coalition has said it is ready to launch an all-out air offensive to drive the militants out of the area, located north of Aleppo, Syria’s most-populous city, but not until there are opposition forces on the ground ready to occupy the terrain. And the more the rebels are engaged in the Russian-aided fight against Assad, the less willing they are to switch their attention to the border.

U.S. officials say that a small force of opposition fighters in the area, including about 130 Syrians trained by the Americans in Jordan who are in direct communication with U.S. forces, have had some success. But their operations are still rudimentary. To delineate their lines from those of the Islamic State and avoid their own casualties from coalition airstrikes, they light tires on fire and warn pilots to avoid the smoke.