Now on both sides of the Atlantic the weapons of war have been enlisted to wage peace. First America's European allies called for deployment of US nuclear missiles on their soil - but only in conjunction with vigorous arms control efforts intended to make deployment unnecessary.
At this moment members of the US Congress are using similar tactics. They are willing to fund a step toward MX deployment on American soil - but only in conjunction with similarly vigorous arms control efforts on the part of the administration.
President Reagan this week responded to Congress in writing, just as he earlier had spoken to assure the Europeans of his willingness to be flexible for the sake of achieving arms control. He can dispel the immediate cry of ''smokescreen'' from a leading congressional opponent of MX; all he has to do now is follow through with actions as dedicated as his words.
Mr. Reagan can rightly argue that arms control is a two-way street. It is up to the Soviets, with their absurdly excessive SS-20s aimed at Europe, to forgo propaganda for progress in the Euromissile negotiations. And they do not inspire confidence in their START overtures on strategic arms when they test a missile that brings questions about whether it violates the unratified SALT II treaty to which both sides have supposedly been adhering.
Moscow will be under greater pressure to join the arms control effort if it faces negotiators with united resolve behind them - rather than lonely voices with constituencies as badly split as Moscow would like.
Therefore Mr. Reagan is on the right track in seeking a realistic linkage of arms and arms control policies to unite his constituencies both in Europe and in his own nation.
The current activity on the home front has been facilitated by the report of his Commission on Strategic Forces, headed by Gen. Brent Scowcroft. Though its composition has been criticized for not being balanced in terms of MX and arms control opinion, it did include members of both parties and various administrations. Without such a bipartisan initiative the MX would no doubt simply remain in the deep-freeze where Congress sealed it last year.
By linking the MX and a proposed small single-warhead missile to arms control , the report gave Congress a fresh opportunity to do the same. When members of Congress asked for assurances that Mr. Reagan went along, he replied with an assertion going farther than before: that he agreed wholeheartedly with the ''essential theme'' of the commission's approach. He defined this as ''the attainment of stability at the lowest possible level of forces,'' and he said he would review the US position on START to develop any necessary modification to reflect the commission's approach.
Such commitment was enough for a House defense appropriations subcommittee to vote funds for research, development, and testing of the weapon (though not the procurement specifically asked for by Mr. Reagan). At this writing some senators were expecting similar assurances from Mr. Reagan, though he had expressed doubts about their specific ''build down'' proposal even while liking the general concept of both sides getting rid of two weapons for every new one built.
Some in Congress predict MX will be defeated anyway, especially with the commission's confirmation of its vulnerability in Minuteman silos. Some would like a concrete display of presidential enthusiasm for arms control, such as naming strong and prominent officials to the quest for it.
A basic element is the need for a bipartisan consensus that will support an effective combination of arms and arms control into the future. Mr. Reagan now has given himself something to build on, a commitment to seeking a consensus that will ''deserve to be sustained from one administration to the next.''