DUBAI (BLOOMBERG) - Iran is assessing 13 scenarios to respond to the US killing of Qassem Soleimani, the influential general in charge of foreign operations.

Even the weakest of those options would be a "historic nightmare" for the United States, Mr Ali Shamkhani, the head of Iran's national security council, was quoted as saying by Iran's semi-official Fars news agency.

The countdown has begun for the US' exit from the Middle East, Iranian Foreign Minister Mohammad Javad Zarif said on Tuesday (Jan 7) in Teheran, warning of war that would last for generations if the region continued to rely on America's presence.

Mr Zarif spoke as the funeral procession for Major-General Soleimani, who was killed in a US drone strike in Baghdad last Friday, moved to Maj-Gen Soleimani's hometown of Kerman.

In Germany, lawmaker Roderich Kiesewetter said some German troops would be temporarily withdrawn from Iraq. In Lebanon, the US embassy tightened security in anticipation of Iranian retaliation, according to a local newspaper.

"Even if the weakest of these scenarios gains a consensus, the implementation of it can be a historic nightmare for the Americans," Mr Shamkhani was cited as saying by the semi-official Fars news agency.

"For now, for intelligence reasons, we cannot provide more information to the media," he said.