Jordan's surprise announcement that it has resumed diplomatic ties with Egypt was seen here as a bold move for this normally cautious kingdom. In an almost casual announcement on the evening news Tuesday, Jordan became the first Arab nation to renew formal relations with Egypt. All but three Arab states - Sudan, Somalia, and Oman - broke diplomatic ties in 1979 after Egypt signed the Camp David treaty with Israel.
''I think it is a new political position for our King to be taking,'' said a knowledgeable Jordanian official. ''It shows that Jordan is not so weak and so afraid that it will sit on the fence forever.''
All day Wednesday, Ihab Wahba, the head of the Egyptian mission in Amman, was accepting congratulatory phone calls at his official residence.
''It was an extremely positive step by Jordan,'' a smiling Mr. Wahba said during an interview held between calls. ''We are very happy.''
Jordanian and Egyptian officials were quick to caution that the decision does not mean that Egypt and Jordan are planning any dramatic new peace initiative. But by renewing formal ties with Egypt, Jordan has tacitly accepted the separate peace that Egypt made with Israel.
Jordan already is being criticized by hard-line Arabs for its action. Syria and Libya issued blistering denunciations. The Israelis, on the other hand, welcomed the move. Foreign Minister Yitzhak Shamir called it a victory for the Camp David peace process.
The Jordanians feel they have much to gain by the timing of their move. The kingdom wanted to signal the United States that it approves of recent statements by President Reagan and Secretary of State George Shultz on the Middle East, the Jordanian official said.
And Western diplomatic sources speculated that King Hussein may also have wanted to put pressure on Palestine Liberation Organization chairman Yasser Arafat to resolve the internal divisions within the PLO and join a moderate Arab front in seeking a negotiated settlement with Israel.
''It could be the King telling Arafat to do something to sort out the PLO, the divisions have been dragging on long enough,'' said a political analyst.
Mr. Arafat flew to Amman early Wednesday morning, on what aides said was a visit planned before the Jordanian announcement was made. The guerrilla chief issued no statement Wednesday.
By formally welcoming Egypt back into the Arab fold, King Hussein is thought to be bolstering the position of Arab moderates who want to negotiate with the Israelis for the return of the Gaza Strip and the West Bank to Arab rule.
An Egyptian-Jordanian alliance could serve as a counterweight to the increasing power of Syria in the region.
''It strengthens the moderate camp of peace,'' said Jordanian Court Minister Adnan Abu Odeh. ''It's a step that should have been taken and now is the time to take this step.''
The Jordanians have been building up to resuming diplomatic ties with Egypt for the past year, officials here said.
Last December, the two nations signed a new trade agreement. Some 80,000 to 100,000 Egyptians have continued to work in Jordan despite the lack of formal relations.
But King Hussein reportedly decided to make the announcement only after Reagan said in a speech Monday to the United Nations that the US will pursue the Middle East peace initiative Reagan introduced two years ago. The plan calls for a Palestinian 'entity' on the West Bank and Gaza Strip confederated with Jordan.
''... I proposed a fresh start toward a negotiated solution to the Arab-Israeli conflict,'' the President said. ''My initiative of Sept. 1, 1982, contains a set of positions that can serve as a basis for a just and lasting peace. That initiative remains a realistic and workable approach, and I am committed to it as firmly as on the day I announced it.''
After Reagan introduced his plan, it was categorically rejected by Israel. The PLO also eventually rejected it, but maintained that it had positive points and could serve as the starting point for future negotiations.
''We did not expect Reagan to make any move before the election,'' one Jordanian official said. ''When Reagan announced that the Reagan initiative was still the US position, it was as if he was announcing to the official world that he is interested in peace in the region.''
For months, the Jordanians have said that the US could no longer act as an honest broker for peace in the Middle East because it is too closely allied with Israel. After the Israeli elections left that country with a government sharply divided on the future of the occupied territories, the Jordanians had all but given up hope of the peace process being restarted.
But a series of events in the past week made the King decide that the Americans might again be willing to enter the process, including the American response to the bombing of the embassy in Beirut.
The Jordanians were impressed, one official said, that the Americans sent Assistant Secretary of State Richard Murphy to the region last week.
Mr. Murphy was dispatched to Beirut supposedly to investigate the bombing. But he also visited Syria and Israel, and is known to be discussing possibilities for an Israeli withdrawal from south Lebanon. Murphy arrived in Amman Wednesday for talks with King Hussein.
The Jordanians have been frustrated for months by what they saw as the American administration's failure to do anything to end the two-year-old Israeli occupation of south Lebanon. The King sharply criticized the administration in a series of controversial interviews and called for an international peace conference.
But the Jordanians now believe that Reagan will probably be reelected in November, and that if he is, he will renew the peace process and may be willing to pressure Israel to make concessions.
There are many flaws in that scenario. There is no indication that the United States is in anyway backing down on its support for Israel, and Israeli Foreign Minister Yitzhak Shamir has reiterated his nation's rejection of the Reagan initiative.
''But the King wanted to put the pieces (of the Arab world) back together and be ready to respond in case something happens after November,'' said a Jordanian journalist and political commentator.
''Our countries (Jordan and Egypt) understand the problem,'' said Ihab Wahba, the head of the Egyptian mission here.
''We have a vision of a solution. We are not really going to compromise on our principles, on the return of land and the rights of the Palestinians. But we are ready to talk if the other side is interested.
''We hope that the rest of the Arab countries will recognize that Egypt has stood fast in its position in regard to all the crucial problems facing the Arab countries.'' The fall and rise of Egypt's influence in the Arab world
NOV. 19, 1977 Egyptian President Sadat becomes first Arab leader to visit Israel. DEC. 5, 1977 Arab states decline Sadat invitation to Egypt to prepare for resumption of Geneva peace conference; Egypt breaks relations with Algeria, Iraq , Libya, Syria, and South Yemen. SEPT. 17, 1978 Sadat and Israeli Prime Minister Begin sign Camp David accords. MARCH 26, 1979 Sadat and Begin sign peace treaty. MARCH 31, 1979 Eighteen Arab League nations and Palestine Liberation Organization agree to sever diplomatic and economic ties with Cairo. MAY 9, 1979 Egypt suspended from Islamic Conference Organization. OCT. 6, 1981 Sadat is assassinated. Mubarak becomes President a week later. DEC. 22, 1983 PLO leader Arafat becomes first of Arab leaders who broke with Egypt to resume ties. DECEMBER 1983 Egypt signs trade protocol with Jordan and Iraq. JAN. 19, 1984 Islamic Conference Organization votes to readmit Egypt. SEPT. 25, 1984 Jordan becomes first Arab state to renew formal ties with Egypt.