Avi K:
Ramban says it (Sefer HaMitzvot, Mitzvot that Rambam “forgot”). According to the Or HaChaim HaKadosh (Devarim 30,20) and the Avnei Nezer (Yoreh Deah 454,6) Rambam actually agrees that it is a mitzva in our time but did not list it as one of the Taryag because of his technical rules for counting mitzvot. Rav Avraham Shapira and Rav Shaul Yisraeli thus ruled that it is prohibited to give land even for peace.
Again, name me the Poskim of today who hold that there is chiyuv to conquer all of EY.
BTW, if you really do think that there is a chiyuv to conquer all of EY today, and that this is a milchemes mitzva which one must put his life at risk for, what on earth are you doing here? Put your money where your mouth is, get a gun, and go conquer Ramallah or die trying!
Syag Lchochma:
See the second part of my last response to Sam2 for an explanation of what I was trying to accomplish with those quotes from the Jerusalem Post.