The interview with Sen. John Glenn (D- Ohio) was in the nature of a timeless tour d'horizon -- an examination of the world view of the man currently rated the front- runner-up for the Democratic presidential nomination. But that report will have to wait. For along the way, Glenn presented a case against Ronald Reagan's handling of Israel's Prime Minister Begin that bears directly on pressing business.

First, the background: just about everybody (except the Begin government) agrees that one key to pumping new life into the Camp David "peace process" is a freeze on expanded Israeli settlement of the West Bank. That was the main sticking point in the president's somewhat inconclusive efforts last week to involve Jordan's King Hussein more intimately in the next step: negotiations for a five-year, transitional period of "full autonomy" for the West Bank and Gaza, with the ultimate status left open.

Hussein's point is that he cannot negotiate on the future of the West Bank while the future is being rapidly foreclosed by an expanded Israeli presence.

Reagan can hardly disagree. His September "initiative" prescribed a "freeze" on further Israeli settlements. But Begin has responded with announcements of a whole new batch of settlements. So the finger points at Menachem Begin.

But Glenn's case against Reagan goes a long way to explain, if not to justify, Begin's defiance. It is Glenn's conviction that what heads of state say to each other through emissaries or in public pronouncements is far less important than what they say to each other in private, face to face. And it is Glenn's well-documented contention that Reagan has never even brought up the subject in his private encounters with Begin.

The president's disinclination to discuss the West Bank directly with Begin is only part of Glenn's case against Reagan's Mideast record. Glenn was aware, from his own conversation with Begin last February (in the presence of the American ambassador to Israel), that the United States had early warning of how slim the pretext would be for an Israeli invasion of Lebanon. He was also aware of how little the Reagan administration apparently cared.

He was worried much earlier about the seeming use of American-supplied weapons by Israel for other than defensive purposes (in contradiction of U.S. law) in the Israeli attack on Iraq's nuclear reactor in June 1981, and the Israeli bombing raid a month later on Beirut.

Glenn is a member of the Senate Foreign Relations Committee. It is traditional practice for Begin to come before that body fresh from White House meetings with the president. And so, on the occasion of Begin's visits to Washington, last year and again this year, Glenn made it his business to ask Begin whether he and Reagan had even talked about either the West Bank or the offensive defensive use of American equipment. He says that he was dumbfounded to hear Begin say repeatedly that those matters had never come up.

After Begin was in Washington in the fall of 1981 to lobby against the sale of AWACS early-warning-and-command aircraft to Saudi Arabia, Glenn had an opportunity to double-check on the first, crucial ReaganBegin encounter. He was a member of a delegation of senators invited to the White House to be lobbied by President Reagan in support of the AWACs deal. He put it directly to Reagan: had he and Begin discussed the West Bank settlements issue or the question arising from the use of American-supplied weapons?

Before Reagan could answer, according to Glenn, Vice President Bush, the national security adviser of that time (Richard Allen) and Secretary of Defense Weinberger broke in one after the other to say that these matters had been dealt with in separate, lower-level discussions. "That wasn't my question," Glenn says he replied. Once again he asked whether the president and the prime minister and dealt with either the West Bank or the possible misuse, under U.S. law, of American weapons. Says Glenn: "There was silence in the room."

Now this strikes me as a significant insight on the practice of statecraft, Reagan- style. More important, it presents the administration with a severe test when Menachem Begin makes his next visit to Washington, now scheduled for early next year.

The consent that the Israelis have obviously read into a consistent record of silence on the part of Reagan over at least a year and a half has carried the de facto annexation of the West Bank by Israel very close to, if not beyond, the point of no return.

If Ronald Reagan cannot bring himself to raise such issues one-on-one, in the only way that seems likely to impress Menachem Begin, John Glenn's critique will take on added weight -- as an indictment, no less, of the way the president has dealt with a crucial aspect of Middle East policy.