With the U.S. Congress preparing to debate a military strike at Syria, Anna Eshoo, D-Menlo Park, and Zoe Lofgren, D-San Jose, have co-authored a letter laying out the major questions that they say must be answered before they make a decision.

In a public letter to National Security Adviser Susan Rice, Eshoo and Lofgren pose a list of questions that they said were not completely addressed during President Barack Obama's briefing with the Congress and top administration officials Monday morning. Participants in the conference call included Secretary of State John Kerry, Secretary of Defense Chuck Hagel, Director of National Intelligence James Clapper and General Martin Dempsey, chairman of the Joint Chiefs of Staff.

The Labor Day briefing was part of the Obama administration's aggressive effort to rally support in Washington for a limited missile strike that would "degrade" the ability of Syria's military to carry out chemical attacks. Kerry, Hagel and Dempsey are scheduled to address the Senate Foreign Intelligence Committee this afternoon about the military operation.

Kerry and Hagel are also due to speak to the House Foreign Intelligence Committee tomorrow. The operation would be in response to Syrian President Bashar Al-Assad's reported use of chemical weapons on Aug. 21 in a suburb outside Damascus, which the Obama administration estimates killed about 1,400 people.

The Monday letter from Eshoo and Lofgren follows last week's letter in which the two congresswomen lauded Obama for his recent decision to seek congressional authorization for a possible military strike. In the Aug. 31 letter, Eshoo and Lofgren said congressional authorization is "legally and constitutionally required – the President cannot legally act alone without the U.S. Congress."

That letter includes many of the questions contained in the new one, many of them revolving around the expected scope and effect of the military operation. What, they ask, does it mean to "degrade" the Assad regime's chemical-weapon capacity? What would the U.S. do if Syria retaliates against Turkey, Israel or Lebanon after the operation? And what other nations, aside from France, would be actual participants in the military attack (as opposed to "mere verbal support")?

Eshoo and Lofgren also ask about the possibility of "world public opinion," particularly in the Arab world, turning against the United States after the attack.

"If, as Secretary Kerry notes the world is outraged at Assad's conduct, why does it fall only to the United States to take actual military action?"

Lastly, they ask about the response the United States can expect from Russia, an ally of Syria and a consistent opponent of a military strike against the Assad regime.

The letter from the two congresswomen comes at a time when the Obama administration is trying to shore up support for the strike from an ambivalent Congress, with some members calling for more aggressive action and others voicing skepticism about America's ability to achieve any positive results with missile strikes in the volatile region. On Tuesday, Obama scored one victory in this effort when Speaker of the House Rep. John Boehner became the third high-profile Republican to voice support for a military operation in Syria, according to the New York Times. Over the weekend, hawkish Republican senators John McCain and Lindsey Graham approved a strike against Syria despite earlier reservations that the limited strike wouldn't go far enough.

Eshoo and Lofgren have yet to take a public position on the Syria operation, though they have requested more transparency in the debate. In their Aug. 31 letter, they urged Obama to make his case for the attack "in the light of public scrutiny, not by 'classified' briefings that are kept from the American people and which members of Congress are prohibited from discussion publicly."

"This debate will have its needed effect only if it is fully transparent," Eshoo and Lofgren wrote.

The Monday letter acknowledges that "this could be war" and that events are "not entirely controllable." Eshoo and Lofgren wrote that they understand that it "might be unwise to publicly report the various scenarios that detail potential adverse consequences from a military attack although we assume that this analysis has taken place."

"However, we feel we must learn of the potential adverse impacts of a military attack before a vote on authorization," they wrote.