Israel was admitted to the UN in May 1949, one year and a couple of days after its declaration of independence as the last British troops pulled out of what had been, for over 25 years, the Palestine Mandate.
Jordan was not admitted to the UN until late in 1955. The Soviet Union opposed its admission because the Western Powers refused to admit each of the Soviet republics separately (which would have given the Soviet Union a big bloc of votes in the UN).
The U.S.S.R. also said that it did not regard the Hashemite Kingdom as being sufficiently independent from Britain.
However, Israeli and Jordanian troops were nose-to-nose all along the UN-brokered armistices lines.
Imagine how it did not improve communications to have Israel a full UN member state, and Jordan refused membership…
It was not until 1955 that a deal was made, whereby just two Soviet Republics (in addition to the USSR) would get a seat and full membership in the world body, the major international organization — and in exchange a group of other states (including Jordan…and Ireland) were also given full membership at the same time.
Haaretz’s Barak Ravid reported today that “The [Israeli] Foreign Ministry has asked senior European Union officials to renew the process of upgrading Israel’s relations with the organization, in view of the renewal earlier this month of direct talks between Israel and the Palestinian Authority”. This is posted here.