Gen. Keith Alexander, director of the National Security Agency, disclosed Tuesday, June 18, 2013 that plots to bomb the New York subway system and the New York Stock Exchange were among more than 50 stopped by secret surveillance programs.

A new poll indicates a majority of Americans support the federal government's surveillance programs that track metadata on domestic phone calls and monitor online activity by foreigners overseas.

But nearly two-thirds of Americans still want Congress to hold public hearings on the issue, according to the Washington Post/ABC News poll released Wednesday.

Sixty-five percent of adults say they support congressional hearings on the matter. The House Intelligence Committee held such a session Tuesday with National Security Agency director Keith Alexander and other top officials in the intelligence community.

Alexander defended the surveillance programs, saying they have helped thwart more than 50 terrorist plots in more than 20 countries since 9/11. While almost all of them are classified, officials revealed details on four cases on Tuesday, including one plot to bomb the New York Stock Exchange and another plan to bomb the New York City subway.

NSA officials are scheduled to brief members of the House intelligence committee on more of the 50 cases Wednesday in a classified meeting.

Fifty-eight percent of Americans support the U.S. phone records and foreign Internet surveillance programs, according to the poll. That falls in the same ballpark as a CNN/ORC International released earlier this week that shows 51% of Americans support the phone records collection, while 66% support the use of online monitoring when targeting suspects overseas.

President Obama, speaking in Berlin on Wednesday, defended the programs, arguing they have struck an "appropriate balance" between civil liberties and security.

The Washington Post/ABC News poll was conducted between June 12 and June 16 with 1,017 adults surveyed by telephone. The sampling error is plus or minus 3.5 percentage points.

 

CNN's Ashley Killough contributed to this report.