Britain wasted no time in reviewing its export licences to the Middle East this week.
Questions about exports to Bahrain were raised in the House of Commons on Thursday.
By the following evening the Foreign Office had already announced it was revoking some licences to both Bahrain and Libya and underscoring its '"deep concern" at continuing violence, as well as advising against all but essential travel to Bahrain.
Whereas even a week ago the export of British tear gas and other riot control equipment to a staunch ally like Bahrain might have drawn little public comment, now the Foreign Office was worried that the equipment could be used for internal repression, and - just as damaging - that the UK could be cast as a willing and hypocritical accomplice.
The shift is symptomatic of Britain's dilemma in how to deal with the current crisis, whether in Bahrain or elsewhere - how to move from close ties with a valued, if autocratic, ally to a more distant and ambivalent relationship with a troubled government, and yet still retain the leverage needed to benefit from a continued relationship if a fully fledged revolution could be avoided.
So why, in the case of Bahrain, does it matter to Britain?
Let's be clear - there may be historical and cultural links and Bahrain was in its time a British-protected state. There may be a healthy exchange of trade between the two countries, Bahrain may carry clout as a regional banking hub.
But it is far from alone among Gulf states in sharing longstanding and close ties with the UK.
And its tiny size means that in comparison to, say, giant Saudi Arabia, the volume of exports or numbers of UK expatriates working in Bahrain is never going to be that high.
No, what makes Bahrain stand out for both Britain and the US is its geographical position and its value as a defence and security hub.
Not only is it home to the headquarters of the US powerful Fifth Fleet, it is also an important base for British maritime forces.
It is a launching pad for military and security activities in the region and an important logistics centre, whether to supply troops in Afghanistan, to combat piracy in the Indian Ocean or to launch counter narcotics and counter terrorism operations.
And its location - a small island bang in the middle of the Gulf - makes it a perfect place to keep a wary eye on Iran, and to send Tehran a message that critical Western oil supplies passing through the Gulf will be protected.
Imagine if it were no longer available as a launching pad - the blow to US and UK security interests would be considerable.
So while the UK may feel the need to voice alarm at continued violence against protesters, and call for a negotiated resolution to the crisis and greater respect for the right of protesters to demonstrate peacefully, there is also another layer of nervousness.
If the turbulence in Bahrain were to lead to substantial reforms, more clout for the Shia minority, an empowered but unpredictable parliament, or even the downfall of the current ruling monarchy, then, they will be wondering in Whitehall, who will guarantee that Western security interests would be properly looked after?
Remember another country in the Middle East that emerged from years of autocratic and military rule to become a lively democracy - Turkey.
And remember the shock the Americans got on the eve of the Iraq war in 2003 when the Turkish parliament vetoed a US-led invasion from the north through their territory.
For Western officials concerned with defence and security, greater democracy in the Middle East may in theory sound a good idea, a source of empowerment and dignity for individuals - but when it comes to security arrangements, it is not always optimal.
London and Washington and other allies in European capitals must be surveying the current landscape anxiously.
Not only is Bahrain under pressure to change. Protests and clashes have now been reported in Djibouti on the north-east African coast - another tiny country that punches above its weight when it comes to strategic importance for the Americans - home to another critical security hub.
To navigate through these troubled waters, Western governments know they need to be seen to support popular demands for peaceful and democratic change.
But privately they must also be hoping that the remaking of the Middle East, if that is indeed what is happening, does not leave their sailors and soldiers without a friendly port to berth in.