CNN reports that North Korea may be preparing a second nuclear test:

North Korea may be preparing to conduct a second nuclear test, a U.S. official with access to intelligence information said Tuesday.

The official says that activity at a second nuclear site in North Korea is looking very similar to activity seen at another site just before the October 9 nuclear test.

The official said buildings and other structures are being fabricated at this second site, possibly in an effort to hide activities from spy satellites.

“It would not be unreasonable to assume the North Koreans are planning a second test,” White House press secretary Tony Snow said Tuesday.

The intelligence official said there are also reports of statements from senior North Korean military officials saying that the government intends to conduct multiple tests.

UPDATE: Meanwhile, North Korea calls last week’s U.N. sanctions a “declaration of war.”