Mandatory army service in the middle of PhD, will it be possible to finish PhD under these conditions? I started attending a university while in highschool, currently finishing my masters and have started working on my phd with the same (very very nice) advisors (who are aware of the following situation).

In less than a year from now, I will be recruited for a service of 5 years in the army (army service is mandatory in my country). As things look like right now, for at least the first 6-12 months I will not be allowed to study but afterwards I will be given the weekends and another half a day or a full day (probably later) every week to study/research.

Do you think it will still be possible to finish my phd during my time in the army? How would you react as a possible collaborator knowing that if you will work with someone the research is "doomed" to take much longer as the other person will not be available most of the time?

(Also, are there any suggestions for things I should do on the year left for me before the army to help my situation later?)
This is likely to depend strongly on the country, but in many country's militaries, technical expertise is highly valued.  I have known a number of people in the US, for example, whose official duty assignment was a Ph.D. program.  I do not know whether this is possible in Israel, but suspect your professors may know, and may be able to advise you.

I would thus advise you to investigate whether it is a possible to proactively reach out to the military people who you will need to deal with, and see if you can opt into a program or line of duty that might support this for you as well: it may require making a longer-term commitment to the military, but if it gets you the career you want, the tradeoff may be worth it for you.