Iraq has been holding two Americans in custody since Monday night, after they apparently crossed the border from Kuwait to visit friends. Now the State Department is scrambling to secure their release through the U.N. mission in Kuwait and Polish officials in Baghdad, since the U.S. has no diplomatic relations with President Saddam Hussein's government. "Obviously we are doing what we should be doing to secure the expeditious release of the two missing Americans," said White House spokesman Mike McCurry, who added that President Clinton had been briefed. The Americans work for a private American firm under contract to the U.N., but U.S. officials said privacy laws barred them from releasing their names. The two reportedly were trying to visit friends in a Danish engineering unit near the southern Iraqi town of Umm Qasr. Iraqi police arrested them just 25 yards inside the country as they were driving back to Kuwait in a white jeep similar to those used by the United Nations.