WASHINGTON, Jan. 28 (Xinhua) -- The Pentagon is seeking to upgrade its bunker-buster bomb to enable it to destroy Iran's most heavily fortified underground facilities, the Wall Street Journal reported on Saturday.
The report, citing U.S. officials briefed on the plan, said Pentagon war planners have concluded that their largest conventional bomb, the 30,000-pound "bunker-buster" bomb, is not yet capable of accomplishing such a mission.
The bomb, known as the Massive Ordnance Penetrator (MOP), was specifically designed to take out the hardened fortifications built by Iran and the Democratic People's Republic of Korea to cloak their nuclear programs, the report said.
It said initial tests indicated that the bomb, as currently configured, would not be capable of destroying some of Iran's facilities, either because of their depth or because Tehran has added new fortifications to protect them.
"Doubts about the MOP's effectiveness prompted the Pentagon this month to secretly submit a request to Congress for funding to enhance the bomb's ability to penetrate deeper into rock, concrete and steel before exploding," the report said.
"The push to boost the power of the MOP is part of stepped-up contingency planning for a possible strike against Iran's nuclear program," the report noted.
It said the Pentagon, which has spent about 330 million U.S. dollars so far to develop about 20 of the bombs, is seeking about 82 million dollars more to make the bomb more effective.
Defense Secretary Leon Panetta was quoted as saying that more development work would be done and that he expected the bomb to be ready to take on the deepest bunkers soon.
In his State of the Union address on Tuesday, President Barack Obama vowed to use all options possible in stopping Iran's bid for a nuclear weapon, but did not rule out a peaceful resolution.
While seeking to curb Iran's nuclear program through crippling sanctions, the president has asked the Pentagon to come up with military options.
The United States has sought in recent weeks to tamp down tensions with Iran, which arose due to moves by the United States and the European Union to target Iran's oil exports, but the Pentagon is pushing ahead with its contingency planning, the Wall Street Journal report said.