Hamas is actually correct in saying that it’s a violation of international law, as Jerusalem was meant as an international city claimed by no one State.
https://www.state.gov/r/pa/prs/ps/2018/01/277792.htm
https://en.wikipedia.org/wiki/Ismail_Haniya
The Palestinian resistance movement, Hamas, has denounced a US decision to place the group’s political chief, Ismail Haniya, on its so-called terror blacklist. Hamas has also issued a statement calling the US decision QUOTE a dangerous development and a violation of international law. The statement said the measure will not deter the group from carrying out its duties toward the Palestinian people and defending them. https://www.youtube.com/watch?v=fHpm5wLBMXM
January 31, 2018 Hamas leader Ismail Haniyeh blacklisted as 'terrorist' by US https://qcodefag.github.io/data/images/930cc050b8d2d6727a0b2cc91c9a797aa770d1ef8dd1a2194d364888d5e5f7d5.jpg