Chaverim, is the shalosh shevuos a halacha or an aggadeta? Hint, try to find it in the Rif, Rosh, Ran, Mordechai, Rambam, Tur or Shulchan Oruch. (You can’t.) But you can find it in the chiddushei *aggados* of the Maharsha. Incidentally, Reb Meir Simcha paskened that they became null and void with the Balfour Declaration, since we were not rebelling against the Umos. Many say that even without that they became null and void with the holocaust, since the last is a shevua on the Umos shelo yishtabdu bahem byisroel yoser midai, and they did not keep their end of the deal.
Practically speaking, where in the world did you expect the Jews to go at the time of the holocaust and the survivors when nobody was letting them in anywhere. When it is pikuach nefesh, you don’t ask shailos.