I would claim that sanctions are extremely effective.The total economic and social isolation of the Soviet bloc hampered their ability to gain technological parity with the West and allowed us to maintain a military advantage big enough to dissuade them from embarking on military adventures.
Russia and China currently face no such embargoes and students and knowledge workers from those countries are still able to work and study here.
The US is finally realizing that this needs to end in order to maintain its hegemony. China is already banned from purchasing the advanced Dutch EUV machines and this could lead to them losing more and more ground in the electronics market if the sanctions are broadened to other Chinese companies.
Finally the West needs to stop allowing Russian and Chinese students to study here and exporting our technological know-how which could eventually be used against us.
In the case of Russia this could be straightforward.In the case of China it's more difficult due to the enormous dependency of the West on Chinese goods and products.