BERLIN (Reuters) - The leaders of Germany’s “grand coalition” have agreed to tighten security measures after the deadly truck attack on a Berlin Christmas market, including tougher steps to deport migrants seen as security risks, officials said on Monday.

Leaders of Chancellor Angela Merkel’s conservative Christian Democratic Union (CDU), its CSU Bavarian sister party and the Social Democrats (SPD), agreed at a meeting in Munich to move ahead with the proposals made last month by Justice Minister Heiko Maas and Interior Minister Thomas de Maiziere.

“A well-fortified government is our answer to terrorist threats,” Maas, a Social Democrat, said in a statement. “We are in agreement that the existing rules must be rigorously enforced, and that we must tighten the rules where necessary.”

Maas said it was critical that those migrants who were ordered to leave the country were actually deported.

The agreement paves the way for Germany’s ruling right-center coalition to implement the package of measures and speed any needed legislation through parliament. Die Welt newspaper reported in its Tuesday editions that the measures also included strict residency controls on asylum seekers.

Security and migration will be major campaign themes ahead of the national election on Sept. 24 in which Merkel is seeking a fourth term.

Merkel’s party has been bleeding support to the anti-immigrant Alternative for Germany (AfD) party which has criticized Merkel’s “open-door” refugee policy. A poll released Monday showed that the SPD, junior partners in the coalition, would triumph if the election were held today.

The country is on edge over Islamist violence after a spate of attacks last year, and questions about why Anis Amri, the 24-year-old Tunisian asylum-seeker who ploughed the truck into revelers at the market, was still in the country despite deportation orders.

German authorities had not sent Amri back to Tunisia because they were awaiting papers from the Tunisian government. He was shot dead by police in northern Italy. He had not been held in Germany because German authorities did not believe he would carry out an attack.

Maas said it was important to enforce Germany’s rules and laws to build long-term acceptance for migration. He said the party leaders also agreed to initiate a program aimed at preventing Islamist militancy.

Coalition sources said SPD leaders rejected a proposal made by the conservatives that would have set up “transit zones” for processing migrants.