The first response to word that Barack Obama is prepared to make contact – albeit low-level and clandestine – with Hamas should be caution.

For one thing, the very act of revealing such a move can make it less likely. If the Obama camp comes under heavy criticism from those opposed to engagement with Hamas, it may be forced to deny it countenanced the idea at all. Obama has been super-careful to say next to nothing during the Gaza crisis – and certainly nothing at odds with the Bush administration. He would clearly not have chosen to make this policy shift public. (That said, it's bound to be welcomed by those in the Muslim world who have been angered by his virtual silence this last fortnight.)

Second, even the limited opening to Hamas apparently under discussion in the Obama circle is pretty conditional. It seems to be premised either on Hamas taking a "decisive drubbing" in Gaza or on a reconciliation with Fatah. Neither of those outcomes is guaranteed.

Nevertheless, those of us who have long believed that peace depends on engaging with all parties to a conflict – and that peace is made with your enemies rather than with your friends – have reason to be cheered by this news, tentative as it is.

It suggests that Obama means to follow through on the principle he articulated repeatedly in the 2008 election campaign: that diplomacy is not some kind of reward for good behaviour, but rather an essential component in any nation's toolkit. The US would never foreswear the use of force to advance its vital interests, yet the Bush administration did precisely that with diplomacy – denying itself that essential tool when it came to the nations it consigned to outer darkness: the axis of evil trio of Iraq, Iran and North Korea, along with Syria and, of course, Hamas.

Obama promised to do things differently, saying he would even speak to Mahmoud Ahmadinejad if it would help. The one group he seemed least keen to meet was Hamas, placing clear and steep conditions on any dialogue. Indeed in April 2008 he slapped down former president Jimmy Carter for meeting the Islamist movement. "We must not negotiate with a terrorist group intent on Israel's destruction," Obama said. "We should only sit down with Hamas if they renounce terrorism, recognise Israel's right to exist and abide by past agreements."

If the latest signals are to be believed, Obama is now ready to soften the edges of those conditions. For those who believe that, whether we like it or not, Hamas is now part of the Palestinian reality and that no peace can ever come unless all the major players on both sides – Israeli and Palestinian – are included, this is a small, unofficial, unconfirmed but welcome move in the right direction.