On 20 September 2020, Ambassador Zhang Jun wrote a letter to the President of the Security Council and Secretary-General of the UN, expressing opposition to the US unilateral announcement on the return of UN sanctions on Iran on September 19.

In his letter, Ambassador Zhang Jun said that the US unilaterally withdrew from the JCPOA in May 2018, and is no longer a JCPOA participant. Therefore, it is illegitimate for the US to demand the Security Council invoke the snapback mechanism. In response to the US letter dated 20 August 2020, 13 members of the Security Council wrote to the President of the Council and clearly stated that any decision or action resulting from the US letter is devoid of any legal, political or practical effect. Their view was also reflected by the President in his conclusion on August 25.

Ambassador Zhang Jun emphasized that given the above, the snapback mechanism shall not be deemed as invoked. The provisions of resolutions 1696 (2006), 1737 (2006), 1747 (2007), 1803 (2008), 1835 (2008) and 1929 (2010) will continue to be terminated pursuant to OP 7 (a) of resolution 2231 after September 20. China is committed to upholding the efficacy of the JCPOA and the authority of the Security Council resolution, and will make relentless efforts towards the political solution of the Iranian nuclear issue.