Scenario: In a future conflict, one of the BRICS nation's infantry have effectively fielded personal shields, with medium long-term mobility. The logistics of the shield is such a way that every single soldier can carry their own. However you can decide whether all of them do or not.
Now, you are the NATO army trying to defeat them. Therefore, you need a develop a method to circumvent their defense. Condition: Anything short of a practical method won't work. Remember: behind whatever you say, NATO soldiers' lives, effectiveness and overall security are on that.
Condition 2: To set the stage, the most likely scenario is that NATO is going to assail BRICS on their own soil. BRICS country tend to be uneven, bumpy, and sometimes hazardous ground. So take such a terrain as the battleground. While in a static defensive they may not need shields, in a high risk convoy escort situation they definitely will.
Condition 3: While I won't state the design of the new technology or the way it's carried, I will state some of the tactics: Initially, they form U or rainbow shaped lines to make artificial defenses. As for movement and pursuit, they will stay defensive and won't try to agress the enemy if they run away. They do have a certain fight zone that they will extend to. The defenders will only extend that zone if long range enemies are harassing them, and they have a clear, otherwise safe path toward those long range enemies. Otherwise the defenders deal with them last. In the meanwhile however, they will simply hold their shields in the direction of the fire. Note: since the bullet leaves an imprint on the shield, the enemy soldier will know where it's coming from, and be able to coordinate that with his team and take necessary counter measures from there.
Condition 4: The BRICS defenders are equipped in such a way that they have medium distance consistent offensive coverage. For example, they all use standard rifles with high effective range ammunition, but they don't carry snipers or machine guns. As for defensive methods, they are mobile infantry, meaning they use natural cover. They have a medium flak jacket that will stop fragmentation damage of a 40mm grenade. This armor won't stop typical NATO rifle rounds even at long distances. The defenders' shields however have a high armor rating, stopping the equivalent of .30AP at point blank.
Condition 5: You have to state what's your army, what they're bringing on the field, and how they're setting up their attack.
Condition 6: If you decide to use your transports as part of the battle, then the defenders will use their transport's .50 turret, and the anti-vehicle launcher that they have. Their transport's armor doesn't stop .50 green tip. The turret's shield however, being made out of HHA, will at long distances. Note that if your transports are destroyed that you will have no ability to come back from the mission any time soon and will have to continue to deal with whatever's in that country until support arrives. Support will only arrive in greater than 3 days.
One thing: This is NOT limited by any means and is only judged by equivalence in relation. That is by power scaling and net trades. State armies can carry their standard weaponry, and since NATO's armies tend to be more powerful, it's going to be more than likely that their weapons will be stronger than the BRICS army's weapons. However as stated the defender's level of armor still stops what NATO has to bring on the field.