The COVID-19 outbreak at the US Embassy in Kabul has grown to 159 cases, according to a diplomatic cable sent Tuesday, CNN reported.

This comes amid a devastating third wave of the deadly disease in Afghanistan.

CNN reported that a source familiar with the cable said it noted that several people at the diplomatic mission are on oxygen or have been medically evacuated from the post, which was put under immediate lockdown last week to try to stem the spread of the coronavirus.

However, the growing outbreak at the embassy has reportedly prompted frustration among some in the diplomatic community over the lack of a vaccine mandate for those posted abroad, which they argue hampers the United States’ ability to conduct effective foreign policy.

CNN reported that an embassy management notice dated June 17 warned that “COVID-19 is surging in the Mission,” noting that there were 114 people with coronavirus and in isolation, one death and several medical evacuations.

“Military hospital ICU resources are at full capacity, forcing our health units to create temporary, on-compound COVID-19 wards to care for oxygen-dependent patients,” the notice said.

CNN reported that according to the embassy notice, “95% of our cases are individuals who are unvaccinated or not fully vaccinated,” and it called for those coming to the embassy to be vaccinated before arrival, noting that “failure to do this puts everyone in the community at risk.”

The surge in cases has fueled tensions in Kabul, sources told CNN, with some pointing the blame at unvaccinated contractors. Most American diplomats, third country nationals and locally employed staff have been vaccinated — the rate is more than 90% of staff in the latter two categories, according to the management notice, CNN reported..

According to an official at a major international security provider for the US in Afghanistan, almost 50% of its American staff in Afghanistan have been vaccinated and nearly all of its non-American staff have been.

State Department spokesperson Ned Price acknowledged the outbreak last week but would not provide specific numbers, saying the embassy had “adjusted its operations to do all we can to ensure the continued safety, security, and health of our staff as they continue to advance U.S. interests and our relationship with the Government and the people of Afghanistan.”

“This includes requiring all staff to telework and to adhere to physical distancing and masking requirements and other applicable regulations,” he said, adding that they “expect that normal embassy operations will resume once embassy leadership is confident that chain of transmission has been broken.”