By Priyath Liyanage
Editor, BBC Sinhala service
The assassination of Foreign Minister Lakshman Kadirgamar comes at a time when the peace process in Sri Lanka is in deep crisis.
Kadirgamar was a Tamil who was popular among the majority
Many of the recent killings in the eastern and northern areas of the country have put a heavy strain on the stalled peace process.
In her recent statements, President Chandrika Kumaratunga has stressed the importance of the negotiations.
She vowed to continue efforts to resume talks with the Tamil Tigers.
On the other hand, Mr Kadirgamar was critical of the concessions given to the Tamil Tigers as a result of the three-and-half-year-old ceasefire agreement.
Even in a recent birthday tribute to the president, he questioned the impartiality of the role of the Norwegian facilitators.
The killing of Mr Kadirgamar will put enormous pressure on the president and her government.
She heads a minority government after her former coalition partners, the Sinhala nationalist JVP, left in protest against the signing of a joint deal with the Tamil Tigers to distribute aid to victims of last December's tsunami.
The JVP always favoured the foreign minister and had backed him to be the prime minister in the coalition government.
Mr Kadirgamar was a Tamil who was very popular among the Sinhala majority.
He was vocal about alleged rebel atrocities over the years, and was instrumental in getting the Tamil Tigers banned in several countries, including the UK and the US.
He campaigned against a separate Tamil Nation and always said a solution would be found within a unitary state.
His international campaign angered the Tamil Tiger leadership.
The finger of suspicion over his killing will be pointed towards the Tamil Tigers. They regarded Mr Kadirgamar as one of their main targets.
If the Tamil Tigers did not carry out the assassination, they will have to publicly deny it and condemn it. The rebels are not known to have accepted responsibility for many of the attacks they have carried out during the past three decades.
If this is the work of the Tamil Tigers, then they are in breach of the ceasefire agreement. Under its terms, they agreed not to carry out any political killings.
'War of attrition'
The foreign minister was a well known figure in the international community. His assassination will increase overseas pressure against the Tamil rebels.
Mr Kadirgamar's killing will also further polarise the people and the political parties of Sri Lanka.
The Tigers say the government is backing a covert war against them
The chief peace negotiator and political theorist of the Tamil Tigers, Anton Balasingham, last Thursday accused the government of "covertly supporting a dirty war of attrition" against the rebels.
He warned that the increasing tension had the potential to explode into fully-fledged armed conflict.
Mr Balasingham also said the government had failed in its truce obligations to disarm paramilitaries allegedly working with the army.
His claims came at a time when both sides were accused of carrying out assassinations of opponents in spite of the ceasefire obligations.
Meanwhile, the critics of the peace process will protest even more against any further negotiations with the Tamil Tigers.
The pressure may not mean a call to arms immediately, but the government may feel that it is increasingly pushed against the wall.