US Secretary of State John Kerry was under fire Monday for saying that a proposed US military strike on Syria would be "unbelievably small."
The comment came as Kerry ended a whirlwind diplomatic offensive in Europe aimed at whipping up support abroad for US military action against the Damascus regime, accused of using chemical weapons against its people.
"We're not going to war. We will not have people at risk in that way," Kerry told a news conference in London after talks with British Foreign Secretary William Hague.
Washington has been trying to convince its allies that Syrian President Bashar al-Assad must be held accountable for his alleged use of chemical arms in an August 21 attack near Damascus.
Kerry offered assurances that any US action would be "a very limited, very targeted, very short-term effort that degrades his capacity to deliver chemical weapons without assuming responsibility for Syria's civil war."
"That is exactly what we're talking about doing -- unbelievably small, limited kind of effort," he said in London.
But US lawmakers, who are due to begin voting this week on whether to give President Barack Obama a green light to launch such strikes, lambasted his comments.
Influential Republican Senator John McCain, a long-time friend of Kerry's who has backed the Obama administration's plan, called the comment "unbelievably unhelpful" in a message on his Twitter account.
McCain has been trying to rally Republican support around the plan, with the White House facing an uphill battle to get it through Congress, particularly the House of Representatives.
House Intelligence Committee Chairman Mike Rogers, who also strongly favors a strike on Syria, said of Kerry's comments: "I don't understand what he means by that."
"That's a very confusing message -- certainly a confusing message to me that he would offer that as somebody who believes this is in our national security interest," he told MSNBC.
Deputy State Department spokeswoman Marie Harf said, however, that Kerry was just trying to allay fears that the United States was preparing for major action.
"Secretary Kerry was merely responding to any fears of a massive military operation with boots on the ground like in Iraq or Afghanistan," Harf said in an email to AFP.
"He has affirmed again and again that when the United States military takes action, the Assad regime will feel it. The US military doesn't do pin-pricks, but the Secretary was making clear that a military action can be both tailored and limited."
Kerry was likely to be quizzed about his comments late Monday when he was due to appear at a classified House briefing right after arriving back in Washington from London.