FACTBOX: Key facts on North Korea's nuclear capabilities

(Reuters) - The United States laid out intelligence on Thursday it says shows North Korea helped Syria build a suspected nuclear reactor destroyed by Israel last year.

Here are some facts about North Korea's nuclear program.

THE FACILITY

- North Korea's nuclear program dates back to at least the 1980s, and is centered at Yongbyon, about 60 miles north of Pyongyang.

- It consists of a five-megawatt reactor, a fuel fabrication facility and a plutonium reprocessing plant, where weapons-grade material would be extracted from spent fuel rods.

- In October 1994, the United States and North Korea struck a deal to freeze Yongbyon in exchange for more proliferation-resistant reactors to be built by an international consortium. That project has been canceled.

ESCALATION

- The U.S. confronted North Korea in October 2002 and accused it of having a clandestine plan to enrich uranium for weapons. North Korea, which denies having such a program, has ample supplies of natural uranium in its territory. In theory, it could enrich uranium away from the eyes of spy satellites.

- In February 2005, North Korea declared for the first time it had nuclear weapons.

- It conducted its first nuclear test with a plutonium-based bomb in October 2006.

THE TALLY

- U.S. officials said the North has produced about 50 kg (110 pounds) of plutonium, which proliferation experts said conservatively would be enough for about eight nuclear weapons -- depending on the quality of the plutonium and weapon design.

DELIVERING A WEAPON

- Experts doubt that the North can make a nuclear weapon small enough to mount on a warhead.

- The North test-fired seven missiles on July 2006, including its Taepodong-2 with a range that some experts said could one day reach U.S. territory. It fizzled soon after launch.

- The backbone of North Korea's air force is an aging fleet of 780 fighters and 80 bombers built with Soviet technology, the South's Defense Ministry said.

Sources: Reuters, Center for Nonproliferation Studies, intelligence reports, Congressional Research Service

(Reporting by Jon Herskovitz)