SEYMOUR JOHNSON AFB, N.C. (AP) _ President Bush told military families today that ''sacrifices still lay ahead'' but declared that the United States now rules the skies in the Persian Gulf war. ''The Iraqi Air Force is no longer a factor,'' he said.

In the second stop of a tour of military bases, Bush met with families of four airmen, two of whom are listed as Iraqi prisoners and two as missing in action. The White House released no details about the meeting and did not identify the families.

Earlier, at Cherry Point Marine Air Station in North Carolina, Bush vowed that the United States and its allies ''will prevail, make no mistake about that. And when we do, we will have taught a dangerous tyrant and those few who would follow in his footsteps that there is no place for lawless aggression in this critical region.''

The president joined a picnic at Seymour Johnson Air Force Base in North Carolina, home of the 4th Tactical Fighter Wing. Nearly all of the military personnel from the base are serving in the Persian Gulf.

''Sacrifices still lay ahead, but we will succeed,'' Bush told a cheering crowd.

''Air superiority is an established fact now,'' he said, ''and the Iraqi Air Force is no longer a factor. We have used our air superiority to go after Saddam's missiles of terror,'' a reference to the Iraqi Scud missiles used for attacks on Saudi Arabia and Israel.

Bush recalled that during his State of the Union address Tuesday night, there was a prolongued ovation in tribute to the troops in the Persian Gulf.

''I hope that Saddam Hussein, in his bunker somewhere in Baghdad, saw every minute of it and understands that we are a nation united in support of our troops,'' he said.

At Cherry Point, the president cautioned that ''achieving our goals will require time and sacrifice.''

Bush's mention of sacrifice was particularly meaningful to the Marines and their families who greeted him at this air station. The first ground casualties of the Gulf War were Marines, 11 killed as allied forces battled an Iraqi incursion into Saudi Arabia on Wednesday and Thursday.

''To all of you - spouses, children, parents, loved ones, Marines - you're doing more than just keeping the home fires burning, your dedication and bravery is lighting the heart, believe me, it is lighting the heart of every American,'' Bush told the crowd at Cherry Point.

''It comes as little surprise,'' said Bush ''that the first ground engagement in the gulf involved Marines and it comes as no surprise that the Marines fought with great distinction and fought very bravely.

''Their professionalism and sacrifice will end the nightmare, I'm absolutely confident of that, will end the nightmare of Iraq's brutal occupation and ensure that Kuwait is once again free.''

''We are on course,'' said Bush. ''We are on schedule and things go well.''

He said, ''Day by day, night by night, Iraq's capacity to wage war is being systematically destroyed.''

The State Department issued its annual human rights report and said ''almost every category of human rights dealt with in this report is severely restricted or nonexistent in Iraq.'' The report cited ''extreme means of torture and summary execution of children as well as adults'' to squelch dissent aimed at Saddam Hussein's regime.

The report also found problems in America's closest ally in the region, Israel, and in anti-Iraq coalition partners Kuwait, Saudi Arabia and Syria.

Although Israel succeeded in reducing tensions with Palestinians in the occupied West Bank and Gaza Strip through most of 1990, the end of the year saw a disturbing upsurge in violence, the department said.

Bush's trip to the bases was his first outside the Washington area this year and his first visit to military installations since he spent Thanksgiving Day with troops in the gulf region.

Bush also scheduled an appearance at Fort Stewart in Savannah, Ga. He was flying on to Florida for a private visit with his mother, Dorothy Walker Bush, 89, at the family home in Hobe Sound, near Palm Beach, before returning to Camp David, Md., for the weekend.

Amid speculation of an impending Iraqi offensive, administration officials were insisting Thursday that the United States would not begin a potentially costly ground war to dislodge the Iraqis from Kuwait until the time was ripe.

Both administration officials and congressional leaders have made clear they hope to confine the fighting to relatively safer air attacks as long as possible.

''When we're ready to move, we'll move,'' presidential spokesman Marlin Fitzwater said. He called the current allied strategy ''exactly right.''

Bush met privately with Jewish leaders Thursday. His visitors later said the president told them he was not ready to mount a ground war immediately.

''He's not anxious for a ground war at this point,'' said Shoshana Cardin, chairman of the Conference of Presidents of Major American Jewish Organizations. ''He trusts that there will be more aerial war.''

She also said Bush promised there would be no cease-fire or bombing pause.