Iranian warplanes bombed and strafed this Iraqi capital tonight for the first time in more than a week as Iraqi armor and artillery in the south deployed in apparent preparation for a major attack on the oil center of Abadan.

The Iranian attack here, about two hours after nightfall, set off large fires and triggered massive antiaircraft barrages. It seemed to have caught Iraqi air defenses unaware, because there was no prior alert.

The night sky was lit up with tracers and missiles for about 10 minutes as the city was totally blacked out. Communications in and out of Baghdad were cut as Iraq's main ground satellite station was shut down, reportedly because of the power blackout.

The attack here was part of a series of air raids by both Iran and Iraq on the 17th day of their war, breaking a relative lull of several days in the air. Iraqi authorities reported that Iranian jets also struck oil targets in the northern cities of Kirkuk and Sulamaniyah but were beaten back by heavy antiaircraft fire after doing only light damage.

In Tehran, news agencies reported, the Iranian joint agencies reported, the Iranian joint military staff said Iraqi planes bombed Shushtar and targets in the area of an Iranian air base near Dezful. Both cities are in Iran's rich oil-producing Khuzestan Province, the main site of the ground war centered around Khorramshahr and Abadan.

Two Iraqi Migs were shot down near Dezful, a key road and rail hub linking the oil region with the rest of Iran, the joint staff reported.

The Iranian press claimed Khorramshar's defenders had pushed back Iraqi forces overnight. But reporters on the scene said that only a few pockets of diehard irregulars were still holding out in the center of the city and that Iraqi forces were pounding artillery and grouping for what was shaping up as a large assault on Abadan farther down the Shatt-al-Arab waterway.

Surviving crewmen said several foreign ships trapped in the Persian Gulf war were swept up in artillery exchanges despite attempts to steam out of the line of fire. [Details on Page A29.]

Tonight's Iranian air attack here abruptly shattered a lull in the capital that had brought near complacence following a series of false airraid alerts over the last three days.

In two weeks, Iraq's capital city had settled in comfortably with the routine of war, pursuing normalcy with unaffected ease and supporting the struggle with Iran with as much machismo as could be mustered.

The ear-piercing wail of air-raid sirens has become so commonplace here that few Iraqis heading for shelter even bothered to crane toward the evening skies for a glimpse of the Iranian Phantom F4 fighter-bombers. The flight to shelter seemed begrudging, as if the inconvenience were both unnecessary and compulsory.

Indeed, in the last five days the bombing alerts have been unnecessary, either because Iraqi radar has mistakenly picked up its own aircraft or because Iranian war planes have precipitously turned to other targets. And obedience to the civil defense law is reflexive because it has been ordered by the government of Saddam Hussein and Iraqis obey the government.

An eerie calm settles over normally bustling Baghdad when the high pitched whine of the sirens resounds through the business district and the bright red double-decker buses abruptly disgorge passengers into the safety of narrow side streets. The streets become filled suddenly with empty cars, as if frozen in time, and the sound of an errant vehicle beating onward in defiance of the rule seems to hang in the air like a taunt to authority.

Civil defense volunteers scurry about ordering people off the streets and cars into the shadows of tall buildings, while police with loudspeakers admonish the curious to leave the rooftops or risk being showered by shrapnel from antiaircraft batteries that ring the city.

There have been 20 air raids in the vincinity since the start of the war, most of them similar enough to one another that Baghdad residents have become adept at following the lightning-fast bombing patterns and the paths of tracers and ground-to-air missiles.

The Iranian Phantoms usually come in two's -- four is the most that have attacked together -- flying low over the Kabir Kuh Mountains about 60 miles to the east in hopes of slipping by radar. Sometimes they bank sharply around the Mansour Hotel, as if it were a racing pylon, and sweep low along the palm-lined river toward south Baghdad's sprawling Dora oil refinery and a big power generating plant below it.

Distance is on the Iranian side in this air war, as the major Iraqi targets are so close to the hostile border and Iraq's Soviet-supplied missiles are not suited best for low flying targets over a city landscape. Stung by repeated bombing runs of Iranian Phantoms along the river's path, the Iraqis recently have begun placing anti-aircraft gun position in the receding waterway.

With the hiatus of bombing attacks on the capital, Baghdad residents have become more casual at night about the blackout rules, often turning their lights on until they approach a police or civil defense checkpoint, where they are likely to be forced to have their headlights spray-painted translucent blue for a $1.65 fee. Outside lighting is prohibited and residents have been ordered to keep a minimal number of lights on inside behind curtained windows, or face a reprimand from door-knocking civil defense wardens. During major air raids the main power supply to the city is cut off to assure total blackout.

But during the day, Baghdad shows little evidence of being the capital of a warring nation. The city's stores and markets, abundantly stocked, continue to do a brisk trade without rationing, and gasoline stations have for the most part been unaffected.

Public services, with the exceptions of bus transport at night, have not been hampered, and the Ministry of Communications today took pride in announcing that normal postal services have been made available at the front for the armed forces, despite the fact that telephone communications are difficult.

Going into the the war with $38 billion in assets, Iraq shows signs of standing up relatively well economically, even though it has sustained severe blows to its oil industry.

The nation's daily 2.8 million barrels of crude oil export, which earned an estimated $30 billion annually, have all been but halted by the war, largely because of damage to oil installations near Kirkuk and large terminals at the head of the Persian Gulf. But economic analysts and Western diplomats estimate that because of huge financial reserves, Iraq could sustain a year or more of such disruptions without defaulting on its debt.

"As far as cash flow is concerned, there is no problem. They are obviously better off than the Iranians, who have a cold winter coming up and not much kerosene. Saddam says he will succeed because he has a strong economy and a stable government, and it is hard to score him on that," said one diplomatic source.

What is more imponderable, however, is the longer-range damage done to Iraq's economy as a result of Iranian attacks on industrial targets, many of them manned by foreign personnel who have left. Before the war, foreigners accounted for about 10 percent of Iraq's work force and their evacuation is certain to affect economic development. Moreover, the war could make foreign workers more reluctant to come here.

One big problem Iraq faces is the stiffness of its bureaucracy, which is not geared for the kind of flexibility needed to renegotiate industrial development contracts abandoned at the outset of the war, according to foreign economic analysts here.

"The most basic decisions require political decisions, and this reality is going to make itself known when it comes time to start talking about redevelopment of industry," an analyst said.

Despite the economic liabilities, Iraqis in the capital appear to be unreservedly in support of the war. Some may be surprised by the depth of Iranian resistance, but public expressions even of such mild surprise are as rare as overt challenges to Saddam Hussein's tight-fisted rule and are overwhelmed by a relentless barrage of war propaganda on television -- uninterrupted hours of war films repeated over and over against the background of martial music and exhortations of patriotism.