WASHINGTON, May 22 -- Japanese long range balloons have made sporadic attacks on the western part of North America during the last several months, the army and navy reported today.
    Some of the balloons are known to have landed or dropped explosives in isolated localities but there has been no damage to property, the joint statement said.
    This was the first time that the public generally had been told of the attacks, although they were known to many newspapermen and others.

    Pastors of Tacoma churches Sunday and teachers in Tacoma schools Monday read official statements regarding danger from the bombs and urging people to beware of any that might land in their vicinity
    The joint statement said the disclosure was being made so that a public safety campaign could be undertaken to prevent possible damage or injury from the balloons.
    There is always a possibility, the statement said, that unexploded bombs may be found in isolated spots, concealed in wooded areas, or buried beneath melting snow.

    With the approach of warm weather and the end of the school season, the statement added, "It is desirable that people and especially children living west of the Mississippi River be warned of this possible hazard and cautioned under no circumstances to touch or approach any unfamiliar object."
    The army and navy said they wanted to reassure the nation that the balloon attacks are so scattered and aimless that they do not constitute a military threat.
    "They should not be viewed with alarm," the statement said.
    The armed services said they took the position that the possibility of saving even one American life through precautionary measures would more than offset any possible gain that the enemy might make from the mere knowledge that some of the balloons had arrived on this side of the Pacific.

    The enemy would like to know the exact time the balloons arrived, the locality and their effect, the statement said, adding:
    "Such information would permit him to evaluate the results of his efforts and possibly correct his methods."
    The statement said this specific information will be kept back from the enemy if possible.
    The balloons, which carry a few small bombs, were described as being of gray, white or greenish-blue paper and about 33 feet in diameter. The main purpose of the bombs, it was said, is believed to be to set brush and forest fires. The balloons are unmanned and cannot be controlled by the enemy.