WASHINGTON -- U.S. intelligence analysts have discovered evidence that South Korea is trying to develop longer-range ballistic missiles while keeping some of the program's key aims secret from Washington, American officials say.
U.S. spy satellites detected fresh evidence of the program's extent last year, and American concerns intensified further after a missile test this year, the officials said. The United States, South Korea's closest ally, has been tracking its missile research carefully for years.President Clinton and his top aides discussed their latest concerns with top South Korean officials this summer. The situation has injected an element of uncertainty into relations at a time when both allies are warily watching military developments in North Korea, which itself has ambitions to build long-range missiles. The Clinton administration has been pressing North Korea to restrain its missile programs.
The spy satellite photos revealed last year that South Korea had built a rocket motor test station without notifying the United States, according to Pentagon analysts who reviewed the intelligence. The station, which includes a large concrete or tempered steel cradle in which rocket motors are locked for firing tests, appeared to have been built secretly as part of a larger South Korean ballistic missile program, the officials said.
In April, South Korea conducted a short flight test of a new missile that appeared to violate its agreements with the United States, American officials said.
For Clinton administration officials already deeply worried about North Korea's missile and nuclear programs, South Korea's apparent efforts to develop a strategic capability of its own have raised the prospect of a regional arms race at a time when North Korea's stability is increasingly in doubt.
South Korea's missile ambitions prompted Clinton to discuss the issue personally with President Kim Dae-jung of South Korea in July, American officials said, and Defense Secretary William Cohen also raised the issue later that month.
Administration officials refused to comment directly on the evidence uncovered by the American spy satellites last year, but one acknowledged that parts of the South Korean ballistic missile program have been hidden from the United States.
"We are interested in greater transparency in their missile development," the official said. "We don't want this issue to become a point of friction in our bilateral relationship."
The officials stressed, however, that no single piece of intelligence had suddenly prompted the administration's efforts to limit South Korea's missile program. Washington has known about South Korea's efforts to develop ballistic missiles for years, they said, and the administration has been working quietly but consistently to contain the program.
"This is an issue of longstanding concern between us," said one American official. "They have been working on a ballistic missile program for a long time, and this is an issue that is raised with them frequently."
A South Korean government official, however, denied that Seoul has sought to shield parts of its ballistic missile program from the United States. "I believe we have kept transparency in the missile field with the United States," said Yoon Joe-shim, an official in the South Korean Embassy in Washington.
While no final agreement between the United States and South Korea has been reached, the Clinton administration has signaled to South Korea that it is willing to accept limited improvements on the range of South Korea's ballistic missiles, American officials said.
Under a bilateral agreement with the United States, South Korea has restricted the range of its missiles to around 110 miles, and its arsenal is largely stocked with older, American-designed systems. South Korea has accepted those restrictions because of its dependence on the U.S. military, which Seoul counts on to provide a strategic deterrence against North Korea.
But now, the Clinton administration has told Seoul that it will accept an increase in the range of its ballistic missiles to 180 miles, the limit established for countries belonging to a group known as the missile technology control regime. The United States also wants South Korea to join that group, thus locking Seoul into limits on the range of its missiles.
"We have been working with them on how this should develop," said one American official. "We have been talking to them about our concerns that they not develop missiles beyond that range."
James Rubin, the State Department spokesman, added that "it is public knowledge that South Korea would like more flexibility in its missile program. The U.S. is sympathetic to its needs and desire for flexibility, and we are hoping to work out an arrangement that conforms to our nonproliferation goals and the missile regime standards."
Yet South Korea appears to be developing missiles with ranges of 300 miles or more to counter North Korean missiles of similar or even longer ranges, American officials and outside experts believe.
North Korea's missile program has made rapid advancements in the past year or two. In addition to its No Dong missiles, which have a range of 600 miles and could hit all of South Korea and parts of Japan, North Korea surprised U.S. intelligence officials in August 1998 by flight-testing a three-stage version of its Taepo Dong 1, an intercontinental ballistic missile that could be capable of hitting parts of the United States with light payloads.
North Korea has also been developing the Taepo Dong 2, an inter-continental missile believed to be capable of carrying larger payloads than the Taepo Dong 1.
Last April, facing the prospect that the North Koreans would soon flight-test the Taepo Dong 2, South Korea flight-tested a new ballistic missile, American officials say. That missile went only about 30 miles, but analysts believe the South Koreans did not fully fuel it to avoid a dispute with the United States, and say it may have a range of as much as 300 miles.
The Clinton administration appeared to win something of a cooling-off period in the Korean missile race in September, when North Korea agreed not to conduct flight tests of the Taepo Dong 2. In return, Clinton agreed to ease some American trade sanctions that had been imposed on the country for nearly half a century.