IT will be no consolation to the families of the three British soldiers killed in Tuesday's bomb blast in Helmand to hear their deaths come precisely at the moment when the Taliban has actually reduced its attacks on coalition forces.

Certainly the first quarter of 2013 has seen a 47% increase in Taliban attacks compared to 2012, but by far those strikes have been against Afghan forces rather than coalition.

Much is often made of what has been dubbed Afghanistan's "fighting season" – as the spring weather improves making it easier for insurgent fighters to move and be resupplied.

This was as true of the 1980s war against Soviet Russia as it is today.

But one of the other main factors behind the escalation of attacks is that the coalition has significantly reduced its overall presence on the small, exposed and more vulnerable forward operating bases they established throughout the countryside during previous surge operations.

As many as 80% of such bases have been closed down or handed over to Afghan forces.

Taliban fighters have been quick to capitalise on this shift by seizing territory whenever possible.

It is expected the bulk of fighting in the coming months will move from southern and central Afghanistan to the more rugged eastern portions bordering the Pakistani tribal regions that facilitate the militants' logistical supply lines from sanctuaries in Pakistan.

Without the air mobility and massive firepower of the coalition, Afghan troops here will face serious challenges in containing a Taliban offensive.

Tuesday's massive roadside bomb attack does not, in itself, signal a change in Taliban tactics.

The militants, however, may well claim that they are laying down a marker for things to come.

Overall, it is the emphasis on attacking Afghan forces that distinguishes a shift in battlefield dynamics. This, and the Taliban's overall strategy of discrediting the government of President Hamid Karzai ahead of next year's presidential election and the planned withdrawal of most coalition combat troops by the end of 2014.