The United States said Thursday it was "fully capable" of defending itself and its allies against any North Korean missile strike, after Pyongyang threatened to launch a nuclear attack.

The U.S. military could deal with any such attack, U.S. officials said, repeating earlier warnings that North Korea would gain nothing by provocations, while stressing they took its threats seriously.

The U.S. Federal Bureau of Investigation has renewed a $1 million dollar reward for information leading to the safe return of a former agent who went missing in Iran six years ago.

Robert Levinson traveled to the Iranian island of Kish on March 8, 2007 as a private investigator looking into cigarette smuggling. He went missing the following day and has not been seen or heard from since.

President Barack Obama will take his charm offensive with Republicans up a notch on Thursday, having lunch with budget hawk and former vice presidential candidate Paul Ryan at the White House.

Hours after supping with a dozen Republican senators to start a dialogue aimed at reviving a stalled "grand bargain" on the deficit and spending, the president will welcome Ryan, a key player in the House of Representatives.

A Republican irate over the Obama administration's refusal to rule out drone strikes on U.S. soil took to the Senate floor Wednesday in a classic filibuster to block the president's CIA nominee.

The issue gained further currency on Capitol Hill with senators from both parties pressing U.S. Attorney General Eric Holder for more details on whether the administration believes such attacks could be justified.

The United States is hoping to forge better ties with Venezuela once the political upheaval caused by president Hugo Chavez's death is over, but admitted Wednesday it may take some time.

"All of us know that electoral campaigns may not always be the best time to break new ground on policy," a senior State Department official, who asked not to be named, told reporters on a conference call.

Venezuela said Tuesday it was expelling a second U.S. embassy official for unauthorized contacts with Venezuelan military officials and conspiracy amid the illness of ailing President Hugo Chavez.

Foreign Minister Elias Jaua said the two Air Force officials were considered "persona non grata" and being kicked out of Venezuela.

The United States wants the rival parties in Bahrain's political crisis to hold talks on resolving the two-year deadlock in their country, U.S. Secretary of State John Kerry said on Tuesday.

"Progress has been made" in Bahrain, he told reporters in Doha, the last leg of a regional tour. "What I did was encouraging ... dialogue (to continue) and to reach a resolution."

The United States and China on Tuesday called on the U.N. Security Council to sanction North Korean diplomats and "illicit" cash transfers to step up pressure on Pyongyang's nuclear program.

But the isolated North fueled tensions, threatening to scrap an armistice that halted the 1950-53 Korean War and warning that it could launch "strong" counter-measures against what it called U.S. hostility.

U.S. aviation authorities said Tuesday they had opened an investigation into a pilot's sighting of a small unmanned aircraft in the air near New York's John F. Kennedy International Airport.

The Federal Aviation Administration said an Alitalia pilot reported seeing "a small, unmanned or remote-controlled aircraft while on final approach" to land at the airport on Monday.

A massive winter storm pounding the northern United States grounded over 1,200 flights, closed hundreds of schools and made roadways and highways impassible Tuesday.

More than a dozen states from Minnesota to Virginia were in the path of the huge storm which had already dumped as much as two feet (60 centimeters) of snow in Montana and 15 inches (38 centimeters) in North Dakota.