There are mixed feelings in defence this morning.
Many in Whitehall worry that the vote in Parliament leaves the prime minister and the British government unable to act quickly to deploy UK forces should they need to in the future, and that this has set a precedent making it far harder to use the armed forces without giving Parliament a decisive say.
Others claim it could potentially prove a fatal blow to the "special relationship" with America.
For some in defence, there is a real fear that the vote makes the UK look like a less reliable military and political ally, while, in contrast, France is again in step with the US on military action.
Some at Nato found the vote deeply "depressing", saying the UK emerges a lesser nation today in terms of its role as a global player.
However, inside the Ministry of Defence, many believe the US and UK's security interests are too deep and too intertwined for this vote to prove any kind of fatal blow, though insiders admit there will be many phone calls taking place by British officials and senior officers to their US counterparts today.
Defence Secretary Philip Hammond has made clear his belief that the vote against action in Syria would "place some strain" on the special relationship with the US, though others have termed it a "disappointment", but nothing stronger.
They point out that both France and Germany avoided taking part in the Iraq War, yet their relationships with the US remain strong.
Analysts say that the UK and US have taken separate paths in the past, not least over Vietnam.
The Cold War may long since be over, but both nations retain an ongoing and deep intelligence relationship, which is unlikely to be affected by Thursday night's events in Parliament.
'No bad thing'
And many British former senior officers are relieved that Parliament has - certainly for now - prevented any deeper UK involvement in Syria, following fears that the "end game" and the longer-term consequences of a punitive strike had not been thought out well enough in strategic terms.
Earlier "war-gaming" scenarios of western military action in Syria did not end well.
Others say that if the government continues to cut its funding for the armed forces, it must also reduce its appetite for action, making this parliamentary brake "no bad thing".
What many will be looking at today inside the MoD is what this means in policy terms for the present and the future.
For example, if the UK wants to deploy special forces in the Middle East, how can that be squared with the parliamentary vote?
And what will happen if the UK wants to deploy forces abroad while keeping an element of surprise?
In Syria, President Assad has now had ample warning and plenty of time to move his commanders and forces - already changing the potential impact of any US strike.