(NBC) -- Secretary of State John Kerry said that a U.S. military intervention would include "no boots on the ground" in Paris on Saturday, after meeting with European Union officials in a bid to drum up support amid international resistance to the plan.
Kerry said that he believes support for a possible attack on Syrian targets is "growing, not receding," and argued that, in light of alleged chemicals weapons attacks by President Bashar Assad's regime, this is not the time for the U.S. to be "silent spectators."
Kerry, who arrived in Lithuania's capital Vilnius on Friday, reasserted his argument that the proposed U.S. strike would be limited and would not change the situation on the ground.
At the conclusion of the EU meeting Kerry had a separate one-on-one with Lithuania's Foreign Minister Audronius Azubalis, and lauded the leader for his support of a military strike against the Assad regime.
"We are very grateful for the strong statement that came out of the meeting on Syria – particularly grateful for the foreign minister's effort to hold the Assad regime accountable for what it has done," Kerry said.
Azubalis said that evidence seems to be mounting against the Assad regime in the alleged chemical weapons attack.
High Representative for Foreign Affairs and Security Policy Catherine Ashton agreed with Kerry that a military strike should be launched, and presented a joint statement strongly condemning the chemical attack. Ashton cast blame on the Assad regime and pressed the UN council to act.
Ashton said that Europeans had agreed that the attack was a blatant violation of international law – "a war crime and a crime against humanity" – and that there is strong evidence that the Syrian regime was responsible for attack on Aug. 21.
"A clear and strong response is crucial to make clear that such crimes are unacceptable and that there can be no impunity," she said. "We must prevent creating a dreadful precedent for the use of chemical weapons in Syria again or elsewhere."
Ashton did not say that they must wait for a UN mandate before a military strike against Syrian targets.
Kerry made phone calls to representatives of at least five countries including Egypt, Mexico and Saudi Arabia on Saturday to garner support for an attack on the Syrian regime, said a senior state department official.
More than 100,000 people gathered in the Vatican's St. Peter's Square on Saturday to observe a prayer vigil for Syria, according to the director of the Holy See's press office.
Military officials told NBC Friday that the White House had asked the Pentagon to prepare an expanded list of potential targets in Syria. President Barack Obama characterized the report as "inaccurate."
"One thing I've got a pretty clear idea about is what I talked with the chairman of the Joint Chiefs of Staff about, and what we have consistently talked about is something limited and proportional that would degrade Mr. Assad's capabilities," he said Friday in St. Petersburg at the Group of 20 summit.
Obama was back in Washington Saturday preparing for an uphill battle to convince members of Congress and a war-weary American public to support military action in Syria. He announced Friday that he would address the nation from the White House on Tuesday.
And on Saturday, the White House announced that the president will tape interviews from the White House with anchors from all three major networks as well as CNN, PBS, and FOX, to be aired on Monday night.
Democratic Leader Nancy Pelosi sent a letter to lawmakers in her party Saturday in which she said she looked "forward to continuing this critical debate" regarding the possibility of military action in Syria.
Democratic Senator Mark Pryor of Arkansas also released a statement Saturday calling on the Obama administration to "prove a compelling national security interest." Until then, the senator wrote, he will not support any action taken against Assad.
The White House believes Syrian President Bashar Assad gassed more than 1,400 people to death, including more than 400 children, in a rebel-controlled neighborhood in late August. Obama has said the world must act to demonstrate that it will not tolerate the use of chemical weapons under any circumstances.
A senior state department official said Saturday the U.S. believes the Syrian opposition is beginning to gain the upper hand, but acknowledged the rebels are not happy with the limited scope of the proposed military action.
At home, prospects of congressional approval are uncertain, with both conservative Republicans and liberal Democrats expressing opposition. Abroad, Obama has faced opposition from Russia and China at the U.N., and by British lawmakers in parliament who voted against military action.
Sen. John McCain, R-Ariz., was among lawmakers who at first expressed disapproval that the American attack plan would not do enough to help the Syrian rebels. He voted for a resolution authorizing force that passed a Senate committee earlier this week.
But McCain was also confronted at a town-hall-style meeting in his district by hostile constituents opposed to any U.S. involvement in Syria.