A series of massive explosions -- the strongest blasts in several days -- rocked the center of Baghdad late Thursday night, and a fiery glow and a huge plume of smoke could be seen rising over the city.

There was no air raid alert before the explosions, which occurred shortly after 11 p.m. (3 p.m. EST), suggesting that allied stealth bombers may have fired missiles into the heart of the city.

Buildings close to the Information Ministry appeared to have been hit.

• Map: The War in Iraq

The strikes came as coalition troops were bulking up their forces on three sides of Baghdad after U.S. paratroopers were airlifted into northern Iraq, where they began setting up a northern front.

Allied commanders said clear weather after two days of vicious sandstorms would allow them to intensify their attacks on Iraqi forces.

Sources told Fox News that U.S. government officials have all but concluded that Saddam Hussein remains in control of his military and is preparing for the battle of Baghdad.

Saddam is believed to be issuing orders as he moves from one underground bunker to the next.

One source said there are thousands of Iraqi forces taking positions in and around the city, even digging trenches downtown.

Iraq's defense minister said earlier Thursday that the real battle for Baghdad will be on its streets, and that Saddam's regime will prolong the war as long as possible.

"The enemy must come inside Baghdad, and that will be its grave," said Defense Minister Sultan Hashem Ahmed.

President Bush, meeting with British Prime Minister Tony Blair at Camp David, said: "Together, coalition forces are advancing day by day in steady progress against the enemy. Slowly but surely, the grip of terror around the throats of the Iraqi people is being loosened."

Blair said: "Iraq will be disarmed of weapons of mass destruction. And the Iraqi people will be freed. That is our commitment. That is our determination, and we will see it done."

The prime minister said two British POWs had been executed, and called it "just one more flagrant breach of the rules of international law and humanity."

About 1,000 U.S. Army Ranger paratroopers from the 173rd Airborne Brigade dropped into Kurdish-held territory overnight, opening a northern front. They secured a snow-dusted airfield, which will be used to bring in supplies and support personnel.

"This tightens the noose against Saddam's forces," said Brig. Gen. James Parker, commander of U.S. forces in the north.

It's the first large deployment of U.S. ground troops in the region; previously, only small groups of U.S. Special Forces were operating along with allied Kurdish fighters.

The move was part of a new U.S. action plan to take the northern region, since Turkey wouldn't allow American forces to enter from there.

The paratroopers, based in Vicenza, Italy, will target the oil fields around the cities of Mosul and Kirkuk, as well as Tikrit, Saddam's hometown and the tribal center for his inner circle.

Another key mission could be to keep order in northern Iraq, which includes splinter organizations and is a base for an Al Qaeda-linked Islamic militant group.

Six warships from the United States, Spain and Denmark entered the Suez Canal on Thursday on their way to the Persian Gulf to support the coalition, Reuters reported. Sources said the ships would reach the Red Sea by the end of the day.

Coalition troops, meanwhile, kept steady pressure on Saddam Hussein's military from the south, the west and the north.

U.S.-led invading forces flew more than 600 bombing missions over Republican Guard formations around Baghdad.

In the south, a British armored unit destroyed 14 Iraqi tanks trying to break out of the besieged city of Basra.

The coalition is defeating the regime "with overwhelming force," Big. Gen Vince Brooks said during a Central Command briefing in Doha, Qatar. The land assault remains "on track," he said.

"We remain true to our stated purposes of defeating the regime and liberating the people of Iraq," Brooks said. "We will not stop until we do so. We will pursue the regime and its control wherever we find it."

There are now 49 countries contributing to the coalition effort.

Sandstorms End, Forces Forge Ahead

In central Iraq, where huge Army and Marine forces are gradually closing in on Baghdad, U.S. commanders were buoyed by arrival of good weather and planned to intensify attacks.

"You'll certainly see us increase our activity in the coming hours, days, given the clearing weather," said a Central Command official.

Brooks said several U.S. units battled successfully against Iraqi forces Thursday.

Near Nasiriyah, more than 30 U.S. Marines were reportedly injured in an accidental exchange of fire between American units.

Kurdish fighters in the north on Thursday crossed Iraqi front lines near Chamchamal, according to a Reuters witness.

Meanwhile, a tank unit from Britain's Royal Scots Dragoon Guards attacked an enemy convoy fleeing Basra and destroyed 14 tanks. It was the third time this week that Iraqi columns have been attacked while trying to get out of that city.

U.S. ground troops may soon enter the city.

The first food aid convoy rolled into southern Iraq Wednesday, greeted by hungry children. Iraqi mines in the port of Umm Qasr has delayed the arrival of a ship carrying 200 tons of aid.

British forces have arrested "a senior Baath party official."

Iraq's health minister, Omeed Medhat Mubarak, said about 350 civilians had been killed and more than 4,000 injured since the war began. That number has not been verified.

Saddam's regime emphasized a claim that two American cruise missiles had killed 14 civilians in Baghdad and wounded dozens more.

U.S. military officials insist they did not intentionally aim at the area and that it may have been an Iraqi missile that landed there or a stray coalition weapon.

Iraqis Use Female Shields, Children Fighters

Local Iraqis say enemy troops are pulling Iraqi children out of their homes as a way of getting their fathers to fight -- and threatening men with execution if they don't.

Jim Wilkinson, spokesman for U.S. war commander Gen. Tommy Franks, confirmed these reports and said male children are being forced to fight in the vicinity of Najaf.

"Once again, we see the regime's terrorist tactics, where they bring the innocent onto the battlefield as they try to do anything to stay in power," Wilkinson said.

Some Iraqi fighters battling Marines from Camp Lejeune in Nasiriyah were using women as shields and had given guns to children, reported Keith Garvin of WTVD, who is embedded with the Marines.

"Unfortunately, some of the children have been firing at our Marines and our Marines have been forced to defend themselves," Garvin said.

At least 25 Marines from Camp Lejeune may have been injured in house-to-house fighting there.

"They have executed prisoners of war ... They have used women and children as human shields and they have pretended to surrender and then opened fire," said the Pentagon's No. 2 general, Marine Gen. Peter Pace. "It's disgusting."

Central Command said Iraqi fighters were using American military uniforms to commit acts against the Iraqi people and to "possibly attack U.S. forces."

Fox News' Greg Kelly, embedded with the 3rd Infantry Division, reported that soldiers there found some of their own uniforms with American name tags on them in a bunker that had been abandoned by some of Saddam's Fedayeen fighters.

Another reporter said an Iraqi soldier wearing one of the division's uniforms was driving an oil truck toward the American troops when he was stopped. The reporter said he was rigged with explosives.

Brooks also cited more discoveries of chemical protection suits at Iraqi oil fields in southern Iraq.

"I think those troops were warned ... for all we know, orders were already given to use chemical weapons," Wilkinson said. "It may not be a smoking gun, but it was a chemical gun."

Pace said Iraq has executed prisoners of war, referring to some of the U.S. Army and British troops, and that Iraqis had engaged in many atrocities since the war began.

Emerging from a committee meeting on Capitol Hill Thursday, Defense Secretary Donald Rumsfeld said Saddam's regime left an Iraqi in the center of Baghdad "not too long ago" with his tongue pulled out so that he bled to death.

Iraq, in turn, accused coalition forces of "kidnapping civilians, shackling them, and regarding them as POWs."

Arab television channel Al Jazeera on Thursday showed a video provided by Iraq of what's purported to be a downed U.S. drone, Apache helicopter, three tanks and a number of armored vehicles that Iraq says were shot down in the mid-Euphrates region of the country.

Fox News' Mike Tobin and Carl Cameron and The Associated Press contributed to this report.