Washington:
President Barack Obama on Saturday warned of a "credible terrorist threat" against America after the overseas discovery of two US-bound packages containing explosives aboard cargo jets, even as the White House said the development would have no impact on his upcoming India visit.
Obama said the packages, which according to the officials originated in Yemen, had been addressed to two Jewish centres in Chicago area.
However, the White House said the latest terrorist plot would have no impact on Obama's upcoming trip to India and other Asian nations.
"Whenever the (US) President travels, we take a very careful look at what the threat environment might be and look at what the terrorist environment is. So we're taking this into account, but at this point there is no effect," said John Brennan, Assistant to the President for Homeland Security and Counter-Terrorism.
Obama is scheduled to leave for Mumbai his first stop in India next Friday; which would be the start of his 10-day Asia trip that would also take him to Indonesia, South Korea and Japan.
In Mumbai, Obama is expected to stay in the Taj Mahal hotel that had witnessed the 2008 terrorist attack.
Obama, who was briefed by his top intelligence officials and national security aide on the latest terrorist threat to the US, told reporters in a hurriedly-convened White House press conference that there had been a "credible terrorist threat against our country."
Obama was first informed about the threat at about 10.35 pm local tome on Thursday and had been updated on the developing plot throughout.
The Administration would not spare any efforts in investigating the origins of the suspicious package, Obama said. He said agencies have "identified two suspicious packages bound for the United States, specifically, two places of Jewish worship in Chicago."
The packages were identified in Dubai and Britain, he said.
"Initial examination of those packages has determined that they do apparently contain explosive material," he said.
Obama vowed to take "whatever steps are necessary to protect our citizens from this type of attack," and announced that there would be "additional screening" of some planes in Newark and Philadelphia. More "protective measures" would be taken for "as long as it takes," he said.