The Turkish parliament has voted to authorize further military operations outside its borders after it struck Syrian targets on Thursday in response to a deadly cross-border mortar attack that killed five civilians.

Deputy Prime Minister Besir Atalay said the one-year measure is not a declaration of war, but intended as a deterrent against agressive action by Syria.

The Turkish official said his government is acting in coordination with international institutions in its response to the artillery shelling by Syria that struck the southeast border town of Akcakale.

Atalay said Syria has taken responsibility and formally apologized for the deaths of the five Turkish civilians, and reassured the United Nations that “such an incident will not occur again.”

Turkish authorities and the opposition Syrian Observatory for Human Rights said Ankara's retaliatory artillery strikes killed a number of Syrian soldiers near the border town of Tel Abyad, but there have been no detailed casualty reports.

Local news reports said at least 10 separate attacks early Thursday targeted the area that Turkish forces identified as the source of the Syrian mortars.

The measure before Turkey's parliament said Syria has carried out aggressive actions against Turkish soil despite repeated warnings and diplomatic initiatives. It said there is now a need to act quickly in the face of additional risks and threats.

Turkey already has a law authorizing military intervention against separatist Kurdish rebels based in northern Iraq.

Syrian Information Minister Omran Zoabi said Damascus is investigating the origin of the mortar fire, and that Syria offers its condolences to the Turkish people.

Turkey's Prime Minister Recep Tayyip Erdogan said Wednesday that Ankara acted within international law and will never fail to retaliate for what he called Syrian provocations against Turkey's national security.

U.S. Secretary of State Hillary Clinton said Washington is outraged at the Syrian mortar strike on Turkey, a fellow member of the NATO alliance.

Turkey sent the U.N. Security Council a letter calling for “necessary action” to stop aggression by Syria. U.N. diplomats said the Council was discussing a possible statement in reaction to cross-border attacks.

NATO ambassadors held an urgent meeting in Brussels Wednesday at Turkey's request, and issued a statement demanding the “immediate cessation of such aggressive acts against an ally.” NATO also urged the Syrian government to “end flagrant violations of international law.”