Secretary of State George Shultz, recognizing the contributions of two U.S. diplomats who died with Pakistan's president in a suspicious plane crash, praised the Americans' work toward peace and freedom.

The bodies of U.S. Ambassador to Pakistan Arnold Raphel and Brig. Gen. Herbert Wassom arrived in the United States Sunday at nearby Andrews Air Force Base.Shultz, who attended the weekend funeral of Pakistani President Mohammed Zia ul-Haq, and Defense Secretary Frank Carlucci led a solemn service on the tarmac at the air base.

Shultz accompanied the bodies from Pakistan. As a band played "America the Beautiful," the flag-drapped coffins were taken from the secretary of state's plane. Raphel was to be buried at Arlington National Cemetery Monday and Wassom will be buried there Tuesday.

"They were over there because of big words. Liberty, freedom, justice, security, prosperity, peace. We hear these words all the time. Maybe sometimes we take them for granted," Shultz said in a prepared statement at the Air Force base.

"I can tell you, most people around the world do not take them for granted. They lack them. They want them. They'll fight for them as the Afghan people with President Zia behind them have been fighting and winning," Shultz said.

Raphel and Wassom died Wednesday when their plane exploded in central Pakistan, killing all 30 passengers aboard, including Zia and several senior Pakistani military officials.

Reports from Pakistan have indicated the plane may have been sabotaged.

Some Pakistani sources have speculated that the Afghan secret service, supporters of Palestinians sentenced to death by Zia for the 1986 hijacking of a Pan Am Boeing 747 jetliner that left 21 people dead, or disgruntled military officers in Zia's government, may have been involved.