Prime Minister Benjamin Netanyahu on Sunday said Israel will be closing its international airport to nearly all flights as the government races to bring a raging coronavirus outbreak under control. “We are closing the skies hermetically, except for really rare exceptions, to prevent the entry of virus mutations, and also to ensure that we progress quickly with our vaccination campaign,” he said.

The entry of highly contagious variants of the coronavirus, coupled with poor enforcement of safety rules in ultra-Orthodox communities, has contributed to one of the world’s highest rates of infections. It also has threatened to undercut Israel’s highly successful campaign to vaccinate its population against the virus.

Late Sunday, the Israeli Cabinet approved what Netanyahu said would be a tight closure on incoming and outgoing air traffic. The government said it would make exceptions for a small number of humanitarian cases, such as funerals and medical patients, and cargo flights.

The order is to begin early Tuesday and remain in effect until Jan. 31. Netanyahu’s office said the order still required parliamentary legislation to be finalized.

Throughout the pandemic, Israel has restricted entry at its main international airport. But it has made exceptions for certain categories of people, including religious students and Israelis returning from abroad, while allowing Israeli tourists to fly to a handful of “green countries.” This limited air travel appears to have allowed highly contagious coronavirus variants from the U.K. and other places to enter the country.

Israel’s Health Ministry has recorded over 595,000 cases of the virus since the start of the pandemic and over 4,361 deaths. New cases of the disease continue to climb, even as the country has launched one of the world’s most successful vaccination campaigns and is in the midst of its third nationwide lockdown.

Israeli authorities have struggled to enforce compliance in ultra-Orthodox communities. On Sunday, religious demonstrators clashed with police in several cities.

Throughout the pandemic, many major ultra-Orthodox sects have flouted safety regulations, continuing to open schools, pray in synagogues and hold mass weddings in funerals. This has contributed to a disproportionate infection rate, with the ultra-Orthodox community accounting for over one-third of Israel’s coronavirus cases, despite making up just over 10% of the population.

In Jerusalem, police fired tear gas and putrid-smelling water to disperse a crowd of hundreds of ultra-Orthodox residents outside a reopened school. Demonstrators cried “get out of here, Nazis” at officers who were filmed arresting participants.

In the coastal city of Ashdod, police scuffled with dozens of protesters outside an ultra-Orthodox school. In the ultra-Orthodox city of Bnei Brak, large crowds of protesters chased away journalists. A policeman fired into the air as he was surrounded by a crowd of protesters.

Five police officers were wounded in the disputes, and at least four people were arrested, police said.

With the country experiencing a raging coronavirus outbreak, the Israeli government last week extended the country’s third nationwide lockdown until the end of January.

Sunday’s clashes were the latest incident of heightened tensions over enforcement of lockdown rules in ultra-Orthodox neighbourhoods in Israel. On Friday, ultra-Orthodox Israelis attacked a police vehicle in the city of Bnei Brak, outside Tel Aviv. A crowd pelted the police car with stones and punctured its tires.