BAGHDAD (AP) — Iraqi forces and Sunni militants battled fiercely for control of the nation’s largest oil refinery on Wednesday as Prime Minister Nouri al-Maliki went on a diplomatic offensive, reaching out in a televised address to try to regain support from the nation’s disaffected Sunnis and Kurds.

Meanwhile, the government asserted that it had retaken partial control of a strategic city near the border with Syria.

Al-Maliki’s conciliatory words, coupled with a vow to teach the militants a “lesson,” came as almost all Iraq’s main communities have been drawn into a spasm of violence not seen since the dark days of sectarian killings nearly a decade ago.

The U.S. has been pressing al-Maliki to adopt political inclusion and undermine the insurgency by making overtures to Iraq’s once-dominant Sunni minority, which has long complained of discrimination by his government and abuses by his Shiite-led security forces.

In Washington, President Barack Obama briefed leaders of Congress on options for quelling the al-Qaida-inspired insurgency, though White House officials said the president had made no decisions about how to respond to the crumbling security situation in Iraq. While Obama has not fully ruled out the possibility of launching airstrikes, such action is not imminent, officials said, in part because intelligence agencies have been unable to identify clear targets on the ground.

Al-Maliki, a Shiite, has rejected charges of bias against Iraq’s Sunnis and Kurds and has in recent days been stressing that the threat posed by the militant Islamic State of Iraq and the Levant, or ISIL, will affect all Iraqis regardless of their ethnic or religious affiliations. He also rejects any suggestion that the Islamic State and other extremist groups enjoy support by disaffected Sunnis fed up with his perceived discrimination.

In a move apparently designed to satisfy Obama’s demand for national reconciliation, al-Maliki expressed optimism in a televised address Wednesday over what he called the rise by all of Iraq’s political groups to the challenge of defending the nation against the militant threat.

The crisis has led Iraqis to rediscover “national unity,” he said.

“I tell all the brothers there have been negative practices by members of the military, civilians and militiamen, but that is not what we should be discussing,” al-Maliki said. “Our effort should not be focused here and leave the larger objective of defeating ISIL.”

Late Tuesday, the prime minister appeared on television with Sunni and Kurdish leaders. They issued a joint statement about the need to close ranks and stick to “national priorities” in the face of the threat posed by the militants.

Still, al-Maliki’s outreach remain largely rhetoric, with no concrete action to bridge differences with Sunnis and Kurds, who have been at loggerheads with the prime minister over their right to independently export oil and over territorial claims.

Al-Maliki’s upbeat assessment came as the military said government forces had repelled repeated attacks by the militants on the country’s largest oil refinery and retaken parts of the strategic city of Tal Afar, near the Syrian border.

The chief military spokesman, Lt. Gen. Qassim al-Moussawi, said Iraqi army troops had defended the refinery at Beiji, some 250 kilometers (155 miles) north of Baghdad, and 40 attackers were killed in fighting there overnight and early Wednesday.

An employee at the oil refinery reached by The Associated Press late Wednesday also said the facility remained in government hands, though one of its fuel tanks was on fire after it was apparently hit by a mortar shell fired by the militants. He spoke on condition of anonymity in exchange for discussing the situation there.

The Beiji refinery accounts for a little more than a quarter of the country’s entire refining capacity — all of which goes toward domestic consumption for things like gasoline, cooking oil and fuel for power stations. Any lengthy outage at Beiji risks long lines at the gas pump and electricity shortages, adding to the chaos already facing Iraq.

Video footage posted online showed smoke billowing in the background from an area near the refinery. Another clip uploaded by the Islamic State militants showed heavily armed fighters arriving in the town, waving black flags out of cars. The videos appear genuine and correspond to AP’s reporting of the events depicted.

There was no independent confirmation of the military’s claims about the Beiji refinery or that its forces had retaken neighborhoods in Tal Afar, which Sunni fighters captured Monday. Both are in territories held by insurgents that journalists have not been able to access. Tal Afar’s proximity to the Syrian border strengthens the Islamic State’s plan to carve out an Islamic caliphate, or state, stretching across parts of the two countries.