Unraveling the threads of terrorism

U.S. officials Wednesday said Mohammed Junaid Babar has turned out to be a tantalizing figure in the investigation into the al-Qaida plot to attack the five buildings in New York City, Washington, D.C. and Newark, New Jersey. He also met top al-Qaida leaders earlier this year in Pakistan.

Babar was actually arrested in March. And as NBC News reported last week, pleaded guilty in secret in June, admitting his part in a plan to bomb targets in London. A huge sweep by British police broke that up in late March.

Babar was born in the U.S. and raised in a New York City suburb. But he has no love for his birthplace.

"I did grow up there. But that doesn't mean my loyalty is with the Americans," said Babar in a November 2001 interview. "My loyalty will, has always been, is, and forever will be with the Muslims.”

Now, authorities are exploring a possible connection between Babar and members of another British cell arrested last week, which included Esa al-Hindi, the man believed to have done most of the surveillance of the U.S. financial buildings himself.

NBC News has learned that investigators now have proof that al-Hindi was actually in the U.S. at the time the buildings were cased.

As for Mohammed Babar, investigators are also exploring a trip he admitted taking earlier this year to South Waziristan, a remote part of Pakistan near the Afghan border, now thought to be the center of al-Qaida's top planners.

He met there with a man U.S. authorities confirm was a top al-Qaida official and delivered night vision goggles, waterproof clothing, and money.

U.S. authorities say Babar is now cooperating with them, and his family has been placed in the witness protection program.

A terrorism expert says the U.S. has made big strides in uncovering the building plot.

"Our ability to connect the dots and to link disparate al-Qaida activities in a number of different countries has improved exponentially since September 11, 2001, says terrorism expert Bruce Hoffman.

That intelligence is paying enormous dividends. On Wednesday, officials said operations to round up more al-Qaida operatives are now underway.