Sand truck defense

One of the challenges facing federal officials today is how to maintain freedom of access to well-known American buildings, such as the White House and the Capitol, while providing as much security for their occupants as is feasible. The balancing act is not new; what is changed is the heightened need to protect against terrorist acts of potentially greater destruction than in the past. It is not an easy challenge.

What brings this into focus for the second time in a month is the warning of bombings against the State Department, which caused heightened security both there and at the White House last week.

Americans have rightly considered these and many other government structures in the nation's capital to be ''their'' buildings, which they can visit, under reasonable rules, to see where and how their government works. It is a fine advertisement for the freedoms contained in the US system of democratic government.

But over the years, prudence has dictated an increasing degree of security to protect their occupants and the orderly processes of government. Procedures at the White House, the Capitol, and other government buildings were tightened earlier this month in the wake of the detonation of a small bomb inside the Capitol.

But more stringent measures are needed to withstand the kind of attack that killed 239 marines in Beirut, when a speeding truck loaded with explosives crashed through light barricades and plowed into the marines' building. Temporary measures were undertaken over Thanksgiving, with the stationing of sand trucks and other vehicles at strategic points around the White House and State Department. Scenic they are not, yet they are more effective preventives than previous measures.

The need now exists to think through what can be done to provide similar degrees of protection, in a permanent and less obtrusive fashion, while maintaining a substantial degree of public access.