If you check the history books I think you will find that Britain and Russia were co- chairman of the peace agreement after the French/ Indo China war under the auspices of the UN so neither of them could really offer assistance to either side except surreptitiously.
'Offering assistance' surreptitiously? Britain? Read some of the books written by USAF/USN aircrew involved in the bombing of North Vietnam and their comments about overflying - and not being allowed to harm - numerous Brit (and other European nations) cargo ships in Haiphong harbour waiting to unload supplies for North Vietnam, with their crews on deck giving them the bird.
TBM Legend is right about the Kiwi Seasprites -v- the Australian ones. The Kiwi models worked and continue to work because they simply refurbished the existing airframes, where the Australians tried to turn an old Apple Mac into an iPod.
As to the RAAF not "really" being involved in the 'Stan... I think there's be a few P3 crews who'd be quite willing to take you to task over that. (But to some, I appreciate, it doesn't really count unless you land your aircraft right on the FEBA every night, break out a MRE and then dig a shellscrape under the wing.)
Meanwhile... back to the title of this thread. The best option would be to hand the MHR-90s to civil contractors (for police, SES work etc?) so they can be what they're designed to be - civil helicopters (not that anyone could afford to operate them) and then buy some real military helicopters.
As the Swedes have done.