If the strikes were meant to deter Assad from using chemical weapons again, then they would have been more widespread, targeting a far greater number of chemical and military installations, and without the substantial warning that was given. Democrats and others denounced Trump's use of the "Mission Accomplished" phrase as odd, incautious and premature.
The phrase is associated with President George W. Bush, who used it in 2003 during the Iraq war but which dogged him for the rest of his presidency.
The Pentagon said Syria fired 40 surface-to-air missiles, but most were launched after the damage was done.
The Syrian government is believed to have been responsible for dropping a barrel bomb with chemical agents on a civilian population near Damascus a week ago.
In May 2003, President Bush stood on an aircraft carrier under a giant "Mission Accomplished" banner and declared that "major combat operations in Iraq have ended" - just six weeks after the invasion.
Western powers have no plans for further missile strikes on Syria but will assess their options if Damascus uses chemical weapons again, Britain's foreign minister said on Sunday as debate raged over the legality and effectiveness of the raids, Reuters reported.More news: Tom Rogic nets as Celtic thrash Rangers in Scottish Cup semi-final
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Later Sunday, Trump sent a letter to congressional leaders informing them in writing of his decision to order the strike.
Haley made clear the United States won't be pulling troops out of Syria right away, saying USA involvement there "is not done". Albeit minor, and a far cry from what Assad deserves for his unrelenting brutality against the Syrian people, the presence in the Mediterranean Sea of the largest USA air and naval strike force since the Iraq War in 2003 indicates that US oversight of affairs in Syria will likely remain, as will the capacity to damage Assad's forces once again.
Haley said the joint military strike "put a heavy blow into their chemical weapons program, setting them back years" and reiterated that if Assad uses poison gas again, "the United States is locked and loaded".
The nighttime Syria assault was carefully limited to minimize civilian casualties and avoid direct conflict with Syria's key ally, Russia, but confusion arose over the extent to which Washington warned Moscow in advance.
"Last year, the focus was on the delivery", Pentagon spokeswoman Dana White said Saturday. The U.S. says it suspects that sarin gas also was used.
"None of these military actions are large enough to deter chemical-weapons use when Assad thinks it's strongly in his advantage". And now you know the full story, ' he said.
In his televised address from the White House on Friday, Trump said the USA was prepared to keep up the economic, diplomatic and military pressure on Assad until he ends a pattern of killing his own people with internationally banned chemical weapons. What happens next, she said, is up to Assad and to his Russian and Iranian allies.