It had been noted during the 1990's that the UN's imposition of ceasefires (usually supported or driven by great powers) had in some cases prevented a relatively unbloody violent conclusion of a conflict and prolonged it very much.
The idea to tell people to stop killing each other (and the enforcement by great powers showing off their big sticks) had a strong charm, and these policies were easy to enact.
They were also mis-used by great powers to press the 'pause' button whenever their preferred party was about to lose.
Those were first and foremost policies of denying the enemy a 'victory', and of preventing the defeat of preferred parties.
The Western great powers advanced on this path farther, and by the time of the civil war in Libya they weren't satisfied to ask for ceasefires or safe zones and threatening with invasion - they actually got a UNSC resolution allowing them to intervene with violence to keep their preferred team(s) from getting defeated. Again, the non-preferred team wasn't allowed to win.
But then there are people who didn't get the cynicism in such policies and are actually naive enough to still buy into the idea that ceasefires, no-fly zones and so on are really first and foremost protective for the civilians.
These naive people sometimes call for ceasefires at the 'wrong' time, such as when the Ukrainian government was finally in the process of collapsing the separatist/infiltrator territory.
The less naive pols didn't join this chorus, of course.
And then there are the really, really inept ones who don't only accept the naive interpretation, but also completely lost an understanding for what the word "war" means. People such as those who now call for a ceasefire, so the remains of flight MH17 can be investigated properly.
They seriously call for a break in a war so something can be investigated.
That's like asking a stadium to wait a minute during a professional sports match so some marker on the grass can have its white refreshed a bit.
That's so very much outlandish and stuck in mindset of peace that I can only expect the Ukrainians and Russians to totally lose respect for such fools.
The Ukrainians have a civil war mixed with a paramilitary aggression at home, and are only days or weeks from settling it for good. I wonder how much stupidity and naïveté it takes to ask them to wait for days or weeks with this.
It's this kind of folly which makes me doubt that leading Western politicians are still capable of strategy, or even only strategic thought.