By Jeremy Bowen
BBC Middle East editor
The crisis prompted by the abduction of an Israeli soldier adds to the many problems already facing Hamas in its new role as the elected government of the Palestinian people.
Feeling the heat: Ismail Haniya is under pressure from all sides
Involvement in the abduction will reinforce the view held by the European Union and the United States that Hamas remains a terrorist organisation.
Until the attack on the Israeli border post, Palestinian Prime Minister Ismail Haniya was believed to have been close to accepting a document that would have implicitly recognised Israel.
Now Mr Haniya faces pressure from all sides and the prospect of a much deeper crisis than the one he was already in.
The original attack on Israeli soldiers in a tank will be seen as entirely legitimate by most Palestinians, not just by his own supporters.
And it will be backed by the Hamas leadership in exile in Syria.
Mr Haniya needs to find a way to end the crisis without looking as if he is doing Israel's work.
His best hope is some sort of prisoner exchange - but Israel, for now, says it will not give in to blackmail. And if the soldier is killed, Israel will take drastic action.
Olmert under pressure
Palestinian Authority President Mahmoud Abbas is also pressing Mr Haniya to get the Israeli soldier released.
He believes that actions like raids and kidnaps are counter-productive. But he has his own problems.
If he cannot help to get the soldier out, his already slim chances of serious negotiations with Israel will go for the foreseeable future.
And it is also a major challenge for the Israeli government of Ehud Olmert.
Both Mr Olmert and his Defence Minister, Amir Peretz, are seen by Israelis as security novices.
An investigation has started after Israel's security service, the Shin Bet, apparently gave the government advance warning of the Palestinian attack.