Syria’s Foreign Minister Walid al-Moualem on Saturday told reporters that any foreign ground troops entering the country would be sent home “in coffins”. His remarks come after the collapse of United Nations-led peace talks in Geneva. Earlier in the week Saudi Arabia said it would be willing to send its troops to join the United States-led offense against Islamic State terrorists in the country.

Al-Moualem said that any ground intervention in the country, that did not have the government’s permission, would be considered an “act of aggression” and that the troops would be sent home in wooden coffins.

Even as the minister made these remarks, fresh offensives against the IS around the city of Aleppo worsened the country’s refuge crisis, sending thousands of people fleeing to the borders. Al-Moualem said the government’s “battlefield achievements” in the area signalled that the end of the five-year crisis was nearing. The offensives are part of the reason talks in Geneva fell apart.

Aleppo was the country’s largest city before the civil war began five years ago. Reuters reported that tens of thousand of Syrians have fled their homes towards Turkey’s borders after an intensifying assault on areas around the city. Turkey has taken in around 2.5 million Syrians so far.